Physics

• Can the Bus Cross the Gap? [Wang, 9/15/1996]
  We want to show that it is possible for a bus to cross a 50 ft. gap in a highway.

• Definition of a Vector [Jim, 02/28/2002]
  I would like a "proper" definition of a vector and how concepts of "magnitude" and "direction" arise in the discussion of vectors.

• Doppler Effect [Rob, 5/19/1996]
  We are having incredible trouble getting any understandable research on the Doppler Effect.

• Headlights, Light Waves, Sound Waves [Gowens, 01/26/1998]
  If you are in a hypothetical car traveling at the speed of light, what happens when you turn your lights on?

• In the Hollow Center of a Large Mass [Lynne, 12/23/1995]
  In physics lecture I was told that if a large mass, such as the earth, were hollow and you were to be in the hollow part, then you would be weightless...

• Mass vs. Weight [Grubb, 01/22/1999]
  Can you give me a definition of mass and how it differs from weight?

• Proof: Earth is Round [Glondys, 8/7/1996]
  How can I explain, using simple trig, geometry, and standard definitions of distance, that the Earth is round?

• Special Relativity [Parrotte, 11/1/1996]
  Can you please explain Einstein's theory of special relativity to me?

• Truth Tables and Computer Circuits [VanEtten, 01/17/2000]
  Can you please explain how to read and draw computer circuit diagrams, how to form truth tables from reading the diagrams, and the logical arguments behind this?

• Why Can't We Break the Speed of Light? [Ilias, 12/10/1999]
  Why can't we go faster than the speed of light with the equipment we have now? How about in the future?

• Why There are 12 Tones in a Scale [Ashely, 12/28/2000]
  Why are there 12 tones in an octave? Can you explain the significance or the equation r^n = 2^m? Also, what's so special about a fifth? Why should the scale be based on the fraction 3/2?

• Gravity [Hunt, 11/1/1994]
  When space ships get close to earth, gravity seems to affect the occupants really fast. Why isn't the effect of gravity a gradual occurrence? Does it have anything to do with that law about any two bodies in the universe affecting each other... and does it have to do with inverse relationships?

• Relative speed [Kolodny, 11/30/1994]
  Two vehicles are travelling at 60 mph. One is a 50-foot flatbed truck with a drive-on ramp lowered down to the roadway. The second is a rear wheel drive sedan only 3 feet directly behind the flatbed truck. It is capable of coming to a complete stop from 60 mph in 120 feet. The truck slows to 59 1/2 mph. Since the car is gaining on the truck at a rate of 1/2 mph, the front wheels of the car begin to slowly move up the ramp. Question: When the rear tires finally make direct contact with the ramp, will the car, which was moments ago traveling at 1/2 mph relative to the truck's ramp, suddenly go from 1/2 mph ramp speed to 60 mph ramp speed and thus crash into the back of the truck's cab section?

• Angle for maximum height using water stream [White, 12/7/1994]
  I am trying to investigate the relationship between the angle a hose would have to be positioned in order to maximize the height of the stream of water of constant pressure.

• Motorcycle in the Air [Tompkins, 1/4/1995]
  When a motorcycle is in the air, why does pushing on the gas make it go up and braking make it go down?

• Daylight Hours and Latitude [Chen, 1/9/1995]
  How does the number of daylight hours on a given day of the year depend on latitude?

• Falling Football [Merr, 1/11/1995]
  If I were to drop a football off the top of Mile High Stadium, how long would it take for the football to hit the ground?

• Deriving Distance from the Energy Conservation Law [Peret, 7/6/1995]
  How do we get S = So+0.5*v*t^2+Vo*t, for a free-falling object, from the energy conservation law?

• Forces of Nature [Earther, 10/9/1995]
  How can a sliding incline rod fall sideways? Is there a force of motion I'm not taking into account?

• Interpretation of the Derivative [Entner, 2/2/1996]
  Derivatives incorporate a temporal component with a spatial component...

• Integration and the Concept of Work [Demeo, 3/19/1996]
  If asked to find the work done by a varying force F(x) = 4x^3 from -4 to +4, using integration the work done equals 0. How can it be physically that no work is done when applying this force over a distance of 8 units?

• Motion of a Particle [Law, 3/31/1996]
  I'd like to know how to solve a problem in which a particle is shot from the ground at an initial known angle and velocity. The force of friction is f=av^3 where {a} is a constant.

• Velocity of an Object in a Hurricane [York, 4/5/1996]
  I am doing my project on the distance an object is thrown by a hurricane...

• Purpose of Integrals [Betz, 4/13/1996]
  I am studing calculus, but the book I am using does not say what integrals are used for, or what their purpose is.

• Finding the Highest Point [Shunn, 4/13/1996]
  A ball is thrown into the air, and its height, h, at any time, t, in seconds is given by h = -16(t-1)^2 = 212...

• Speed down a Hill [Senior, 4/17/1996]
  How fast is an object going at the bottom of a 14.9m hill, if it starts at the top going 3.0 m/s?

• Work and Energy Problem [Speak, 5/14/1996]
  The mass of a loaded helicopter is 1500kg. How much energy does its engine expend in ascending vertically for 120m?

• How Fast Does the Man Fall? [Sadler, 5/22/1996]
  If a 180 lb. man drops 1150 feet from a building, how many km per hour will he be going when he hits the ground?

• Turning in Dance [Fan, 5/30/1996]
  I am interested in finding out how a dancer is able to sustain a turn. What roles do angular velocity and acceleration play?...

• Doppler Effect and Math [Brian, 6/1/1996]
  How is the Doppler Effect related to mathematics?

• Escape Velocity [Hautree, 6/13/1996]
  How did Einstein work out how fast you need to go to get off the earth?

• Math-science Materials on Flight [Cushman, 6/16/1996]
  We are looking for math-science materials on flight for grades 7-9, for beginning to very advanced students.

• Earth's Rotational Speed [Tony, 6/24/1996]
  Should the earth's rotational speed be referred to in revolutions per... or in miles per hour?

• Proportions for a Chemical Solution [Fair, 6/24/1996]
  I need to mix up a 10 percent solution that contains a dry chemical...

• Mathematics of Projectile Motion [Platon, 7/7/1996]
  A stone is thrown to hit a bird at the top of a pole. At the instant the stone is thrown, the bird flies away in a horizontal straight line... find the horizontal component of the velocity of the stone.

• Significance of e = mc^2 [Futuredrum, 7/26/1996]
  What does e = mc^2 mean?

• Lifting an Object of Changing Mass [Ponte, 7/28/1996]
  Suppose you grab the end of a chain that weights 3 lb/ft and lift it straight up off the floor at a constant speed of 2 ft/s: determine the force as a function of height; how much work do you do in lifting the top of the chain 4 feet?

• How Long is the Stone in the Air? [Chen, 8/5/1996]
  A stone is thrown from the ground and returns to the ground... what is the total time of flight?

• How Long Until the Bomb Hits the Ground? [James, 8/25/1996]
  A bomber flying at 32,000 feet over level terrain drops a 500-pound bomb...

• Formula for Gravity [Gsch, 9/2/1996]
  If I throw a ball straight up in the air at 40 miles an hour, how long will it take for the ball to come down?

• Rock Falling From Building [Smith, 9/12/1996]
  A rock is dropped from a tall building and hits the ground at 224 ft/ sec. How long did it take for the object to fall?

• Acceleration [Larrys, 9/12/1996]
  A 10-kg object accelerates at 60 m/s^2. What would be the acceleration of a 30-kg object?

• Volume, Mass, Density [Claug, 9/14/1996]
  A flask that can hold 158g of water at 4 degrees Celsius can hold only 127g of ethyl alcohol. What is the density of ethyl alcohol?

• Meaning of Derivative [Tsang, 10/12/1996]
  What's a plain English meaning of the derivative?

• Force = mass x acceleration (F = ma) [Frazier, 11/23/1996]
  Find the magnitude of the earth's acceleration toward an apple.

• Electrical Relationships [Fishman, 12/10/1996]
  The resistance in an electrical circuit is related to the diameter of the wire and the length of the wire. How does resistance vary with diameter?

• Boiling Point of Water [Radcliff, 01/29/1997]
  Is there an equation that predicts the boiling point of water as the pressure is increased?

• Weighted Coin Project [Spivak, 02/01/1997]
  Analyze the results from flipping a non-weighted coin and a weighted coin.

• Stopping Distance [Marshan, 02/25/1997]
  A car is traveling at 25m/s. The brakes are suddenly applied; how far will the car slide once the brakes are applied?

• Expanding Water [Pogrebin, 03/12/1997]
  Why does water expand when it freezes when other materials contract?

• Rate of acceleration/gravity [Mangan, 04/09/1997]
  If a ball is dropped from a building and hits the ground after 3 seconds, how tall is the building?

• Alcohol Solutions [Samoylo, 04/22/1997]
  How many liters of a 14 percent alcohol solution must be mixed with 20 liters of a 50 percent alcohol solution to get a 20 percent alcohol solution?

• Centripetal Acceleration [Ward, 05/05/1997]
  When a vehicle is going around a curve, are the forces balanced?

• Significant Figures and Scientific Notation [Smith, 05/21/1997]
  How do you tell how many significant figures a number has?

• Absolute Speed [MacPhee, 08/12/1997]
  The absolute speed, within the Einsteinian universe, is c (the speed of light). If a ship going 1/100 of c shines a flashlight, what could happen to the light emitted?...

• Mass and Weight [Annie, 08/16/1997]
  Why are mass and weight both measured with the same unit? If weight is different on the moon and mass is not, what is the difference?

• Effect of Gravity on a Stalled Jet [George, 09/05/1997]
  If a 747 jet is flying at 30,000 feet and the engines stop working, will it glide to a reasonably safe landing? Or will it fall straight down?

• Light and the Theory of Relativity [Bennett, 10/15/1997]
  Based on the theory of general relativity, where the faster something goes, the slower time goes, how come light can go anywhere?

• Free Fall [De Souza, 10/16/1997]
  A ball with a mass of 0.5kg is dropped from a height of 190cm...

• Coefficient of Friction [Cliff, 10/17/1997]
  An explanation of static and kinetic friction.

• Breaking the Sound Barrier [Mills, 10/21/1997]
  I am trying to find a way to incorporate breaking the sound barrier into a math lesson for my third grade class.

• Black Holes [Kang, 11/12/1997]
  Imagine an observer outside a black hole watching someone wearing a clock moving into the black hole...

• Differentiation Problem [Confer, 11/15/1997]
  A light shines from the top of a pole 50 ft. high. A ball is dropped from the same height at a point 30 ft. away from the light...

• Angle of Flight [Joel, 11/27/1997]
  A fly is sitting at 12 o'clock on a frictionless clock. He takes a step to one side and begins to slide down the clock...

• The Math Behind Music: Pitches, Scales, Geometry [Angelica, 12/03/1997]
  Connections between music, physics, and math.

• Cylinder on an Inclined Plane [Fieldhouse, 12/17/1997]
  Is there a formula to determine the time it will take for a uniform cylinder to travel a distance along an incline of varying degrees?

• Einstein [Trujillo, 12/18/1997]
  I am in fourth grade. Can you explain E = MC^2 in simple language?

• Falling Chain [Ilya, 12/31/1997]
  A chain 1 meter long is lying on a table with 25 cm. of it hanging in the air. It starts to fall without friction; how long will it fall?

• Radioactive Decay of an Isotope [Butler, 01/05/1998]
  I know the decay of the 226Ra isotope involves the use of logarithms (an exponential function ae^x), but I'm having trouble fitting my information to my equation...

• Why Do We Have Leap Year ? [Wong, 02/25/1998]
  Why do we need to have one extra day each 4 years?

• Speed of a Rotating Disc [Yeo, 03/01/1998]
  The outer edge of a CD travels farther than the inner edge - does the outer edge spin faster?

• Maximizing Horizontal Distance [Carter, 04/10/1998]
  Using algebra, prove that an object needs to be thrown at 45 degrees to travel the greatest possible horizontal distance.

• Travelling at Light Speed [Crummy, 04/11/1998]
  How much time would it take to go to Mars or Jupiter at light speed?

• Over the Right Field Fence [Porter, 04/11/1998]
  What would be the distance of a hit from home base over the top of a 30 ft. high right field fence?

• Colliding Balls [de Garavilla, 04/28/1998]
  A 5 kg ball attached to a pendulum is let go from a 45 degree angle causing the 5 kg ball to collide with an adjacent 3 kg ball...

• Unit and Basis Vectors in Three Dimensions [Jagerman, 05/09/1998]
  Explanations and uses of unit vectors and basis vectors.

• The Angles of a Tetrahedron [Bryan, 07/08/1998]
  Why is the angle from one vertex to the exact center of the tetrahedron around 109.5 degrees?

• Using Vectors in Geometry and Physics [Jenna, 07/10/1998]
  How do you use vectors in problems about medians, areas, and acceleration and velocity?

• Traveling Trains and Nonlinear Systems [Shen, 07/16/1998]
  A train leaves town A and travels 540 miles at a uniform speed, followed an hour later by another train.... What were the speeds of the trains?

• Vector Components, Magnitude, and Direction [Tan, 07/23/1998]
  Given the magnitude and direction of vectors M and M+N, find the components of N and the magnitude and direction of N.

• Quadratics in the Real World [Makhni, 07/30/1998]
  Do you have any real world examples of uses of quadratics? For example, how are parabolas used?

• Summing an Oscillating Series [Anonymous, 08/10/1998]
  Does 1 - 1 + 1 - 1 + 1 - ... equal 1 or 0

• Tides and Simple Harmonic Motion [Liao, 08/11/1998]
  After low tide, find the soonest that a vessel requiring a minimum water depth of 15m can pass through an inlet...

• The Schroedinger Wave Equation [Adam, 09/10/1998]
  Can you help me understand the concepts behind Schroedinger's wave equation?

• Fourier Transforms [Salum, 09/17/1998]
  What is Fourier Transform and what is it used for?

• Interpolation Polynomials and Linear Regression [Cathala, 10/09/1998]
  I need to find the polynomial of a temperature curve using some data I have gathered.

• Shot Out of a Cannon [Langridge, 10/12/1998]
  A performer is shot out of a cannon at 30 degrees from the horizontal, to land 20 meters away... What should his initial speed be?

• A Function for Damped Simple Harmonic Motion [Liao, 10/17/1998]
  The end of a plastic ruler is vibrating in damped harmonic motion. Find an expression for the position of the end of the ruler.

• Convex Lens Algebra [Pudniks, 11/09/1998]
  A focused image from a convex lens is projected on a screen at 3x magnification. What is the focal length of the lens?

• Measurements on a Logarithmic Scale [Tori, 11/21/1998]
  What kinds of measurements are done on a logarithmic scale? What physical properties make a logarithmic scale more appropriate?

• Physics: Collisions [Grahame, 12/17/1998]
  Given the conditions of a collision, find the velocity of one element after collision.

• Eigenvalues [Zuber, 12/18/1998]
  What is an eigenvalue and how is it used?

• Deriving the Arcsin Formula [Suzio, 01/24/1999]
  Why is the arcsin(A) = pi/2 + bi, for some b? How can you derive the inverse sine formula (i.e.: arcsin)?

• Ships in the Fog [Kelly, 02/01/1999]
  Given the locations and speeds of two ships, find whether (and when) they will collide.

• Moment of Inertia of a Solid Cone [Anonymous, 02/03/1999]
  Find the Moment of Inertia of a solid cone in terms of its height and base.

• Rotation of Rigid Bodies [Anonymous, 02/05/1999]
  Rotation of rigid bodies, and the kinetic and potential energies involved.

• Velocity and Time [Jenny, 02/11/1999]
  A car averages 30 km/hr the first half of a trip, and 50 km/hr the second half of the trip. What is the car's average velocity for the trip?

• Anomalous Addition [Greg, 02/17/1999]
  Is it true that sometimes 2 + 2 = 5?

• Imaginary Numbers [Matt, 02/28/1999]
  What jobs and professions use imaginary numbers?

• Bicycle [Maureen, 03/03/1999]
  A problem on linear and angular speed.

• Distance to the Sun [Buchholz, 04/16/1999]
  Find the distance from Earth to the sun when t = 90 days...

• Gravity [Al-Sayyad, 05/07/1999]
  Which ball will hit the ground first...?

• Gravity [Husni, 05/21/1999]
  Why does any free-falling object fall at the rate of 9.8 metres/ second^2 despite its mass?

• Curl of a Vector Field [Arumainathan, 05/22/1999]
  What does the term curl mean in math, and how do we define it in terms of fluid mechanics?

• Weight of a Whale [Diggens, 05/24/1999]
  How do you find the weight of a whale?

• How High Did My Rocket Go? [Joey , 05/28/1999]
  We were 15 feet away from a rocket at launch and measured an angle of 89 degrees on the first launch and 67 degrees on the second. Can you tell me how high it went?

• Mass vs. Weight [Ryan, 05/27/1999]
  If you calibrated a scale to read pounds (mass) on earth and took it to the moon, how would you calculate mass and weight on the moon?

• Carbon Dating [Vicky, 05/27/1999]
  Bones A and B are x and y thousands of years old, respectively. Bone A contains three times as much Carbon 14 as bone B. What can you say about x and y?

• Development of Einstein's Equation [Brown, 06/02/1999]
  What equations and principles did Einstein use to come up with the equation e = mc^2?

• Percentage of Alcohol in a Solution [Nycole, 06/02/1999]
  How do I find the percentage of alcohol in 30 liters of a solution that is mixed with 5 liters of a 90% alcohol solution?

• Examples of Cooling, Growth and Decay [Rangwalla, 06/03/1999]
  Can you give some real life problems involving Newton's cooling method, logistic growth, and exponential growth and decay?

• Proportionality and Absolute Temperature [Sean, 06/06/1999]
  If a gas occupies 100 liters at -13C, what is its volume at 26C? Why do I need to convert the temperatures to Kelvin?

• Mass Gain in Relativity [Holte, 06/06/1999]
  At what speeds would an object experience a 400% gain in mass according to the theory of relativity?

• Mixing Copper-Silver Alloys [Agnes, 06/09/1999]
  How much of each type of two copper-silver alloys is needed to produce 1.2 kg of alloy containing 62% pure silver?

• Plane Flying Parametrically [Jason, 06/28/1999]
  How can I find out when a plane, whose position approaching an airport is described parametrically by P_t = (1000,500,900)+ t[-100,-50,-90], will be closest to the traffic control center, located at (24,11,13)?

• Rate of Flow Through a Pipe [Pitchford, 06/30/1999]
  How much fluid would be dispensed after 1 hour from a line 3/8" in diameter at a pressure of 150 psi?

• Speed of Sound in a Rod [Johnson, 07/05/1999]
  How long is an iron rod if a sound originating at one end is heard in the rod 1 second before it is heard in the air?

• Adding Velocities in Relativity [Bigari, 07/12/1999]
  A train is moving at 60 mph as measured by an observer on the ground outside... A man is walking on the train at 5 mph as measured by an observer standing on the train...

• Weight of a Gallon of Water [Harris, 07/29/1999]
  How much does a gallon of water weigh?

• Safe Passing Distance [Miller, 07/30/1999]
  If a car traveling 55 mph passes a car traveling 50 mph, what distance does the faster car travel to get around the slower car?

• Questions About Math [Nwasokwa, 07/31/1999]
  Why was the Cartesian plane invented? Were the more abstract branches of math developed just for fun? What is chaos theory? Why isn't Einstein's equation e = mc^3?

• Work Needed to Lift a Leaky Bucket [Allison, 08/01/1999]
  How can you calculate the amount of work needed to lift a bucket of water to the top of a well if there is a hole in the bucket causing water to leak out at a rate proportional to the height of the water in the bucket?

• Calculating a Mirror's Reflection [Brandon, 08/08/1999]
  How can I find the angle and the point on a mirror to shine a light at in order to illuminate an object?

• Compressing a Spring - Hooke's Law [Cozzone, 08/09/1999]
  What work is required to compress a spring from a natural length of 4m to 2m if a force of 6N is required to compress it to 3.5m?

• Two Cars [Sandi, 08/11/1999]
  How long does it take car B to draw even with car A, and how far does car B travel?

• Ohm's Law and Battery Life [Stongle, 08/18/1999]
  Given a 12V battery with 275 cold-cranking amps and a load of 12V at 7.2 A on it, how long should that battery run the load?

• Wile E. Coyote Lands in the River [Saddie, 08/20/1999]
  Wile E. Coyote is standing on a springboard atop a high cliff. Road- runner drops a boulder on the other end of the springboard, sending Wile up at an initial velocity of 4 m/s. At what time will he land in the river, 120 m below the top cliff?

• Young's Formula [Smith, 08/21/1999]
  Calculating a child's dose of medicine based on the adult dose.

• Galilean Transformations [Kurt, 09/01/99]
  Could you please explain to me the basic principles of Galilean transformation, and provide an example?

• Mass versus Weight [Parks, 09/09/99]
  Do mass and weight refer to the same thing on earth? Is mass equal to weight?

• Radius of a Racing Circle [Hocking, 09/20/1999]
  How can I find the equation for the radius of a 'racing circle' (the fastest path a racecar can take through the corner defined by the quadrants of two circles), an arc sandwiched between identical quadrants of two concentric circles?

• Will the Train Stop in Time? [Pinky, 09/21/1999]
  The engineer of a train traveling at 80.0 m/s sees a car stalled on the tracks 2000 m ahead and immediately applies the brakes; the train slows down at the rate of 1.50 m/s squared...

• Monkey Climbing a Chain [Huma, 09/22/1999]
  A 20-lb. monkey is attached to a 50-ft. chain that weighs 0.5 lb. per (linear) foot...

• Altitude of a Model Rocket [Swayze, 10/26/1999]
  I need an algebraic formula that determines the altitude of a rocket based upon inclination observations of three ground observers.

• Molar Heat Capacity of a Gas [Ang, 11/17/1999]
  If the volume of n moles of a monatomic perfect gas with an initial volume V and an initial temperature T is halved at a constant rate while its temperature is doubled at a constant rate, how can I prove that the work done to the gas is given by W = nRT*(3*log[2]-1)?

• Balancing Chemical Equations [Katie, 11/21/1999]
  How do you balnce a chemical equation like C2H6 + O2 = CO2 + H2O?

• Surface Areas of Soap Bubbles [Alex, 11/30/1999]
  If you build a frame shaped like a tetrahedron and dip it in bubble solution, why do all of the faces of the bubble collapse to a point in the middle of the tetrahedron?

• Is an Electron a Particle or a Wave? [Aleem, 12/02/1999]
  Can you explain to me whether the electron is a particle or a wave? Electrons diffract like a wave, but also have a mass like a particle. How does this work?

• Circular Motion and Acceleration [Chadwick, 12/03/1999]
  How can an object experiencing circular motion always be accelerating toward the center if the distance from the center is constant?

• Finding the Velocity of a Missile [Daubenspeck, 12/10/1999]
  If the angle of launch is 45 degrees and the distance to the target is 1000 m, what is the velocity of the missile?

• Finding a Formula That Fits the Data [Mullen, 01/26/2000]
  How can I find a formula that fits a chart of tensile strength data I've collected?

• Stroke and Bore of a Piston [Walsh, 05/11/2000]
  How can I determine the distance between the top face of a piston and the top of the cylinder head, and the capacity of a double-acting 8-cylinder diesel engine, for a ship with bore 1 m and stroke 1.3 m?

• If the Earth Stopped Rotating... [Bryan, 05/11/2000]
  If the Earth were to stop rotating, would objects weigh less or would they weigh more?

• Carbon Dating the Shroud of Turin [Sullivan, 05/16/2000]
  In 1988, scientists found that the Shroud of Turin contained 91% of the amount of carbon-14 contained in freshly made cloth of the same material. How old is the Shroud according to the data?

• Heat Supplied and Heat Loss of a Furnace [Lehman, 05/17/2000]
  Heat is supplied by a furnace at a constant rate, but is lost at a rate determined by the difference between its temperature and the temperature of its surroundings...

• Relative Density [Guerra, 05/18/2000]
  A solid object floats in water with three-fourths of its volume beneath the surface. What is the object's density?

• Solving a Decibel Noise Equation [Hazelden, 05/23/2000]
  How do you rearrange the formula 50 = 94.5 - 20log(r) - 8 to solve for r?

• Parallel and Series-Parallel Resistance [Denning, 05/24/2000]
  How do you find the total resistance of resistors in parallel or in series-parallel?

• The Physics of Baseball [Spatz, 07/11/2000]
  How does a baseball move when it is pitched?

• Adjusting Gear Sizes [Rob, 07/14/2000]
  Some material is to be cut into 4" pieces that are 1/8" apart by passing it through two sets of vertical rollers connected by a gear. What diameter of the second bottom roller will give the right separation?

• Balancing Chemical Equations [Kneezel, 09/21/2000]
  Is it possible to create a finitely terminating algorithm to balance a chemical equation?

• Range of the Coefficient of Friction [Kapa, 10/18/2000]
  Can the coefficient of friction be greater than one?

• Series and Parallel Circuits [Kirsch, 10/18/2000]
  Can you show me how to calculate voltage, current, resistance, and power in a series-parallel circuit?

• Projectile Dynamics [Peter, 10/21/2000]
  A particle is projected with initial velocity v and angle theta in a parabolic path. How can I show that at time t, when the angle to the horizontal is gamma, tan(gamma) = tan(theta) - (gt/v) sec(theta)?

• Simulating Sound Waves [Kay, 10/27/2000]
  How can I simulate a sound wave that reaches a maximum height every seventh crest?

• How Much is a Mole? [Lindsey, 11/17/2000]
  How many grams are in a mole?

• Correcting a Speedometer for a New Wheel Diameter [Mike, 11/28/2000]
  A speedometer was designed for a wheel diameter of 65 cm. When a 75 cm wheel is used, the information from the road speed sensor is wrong. How must the input frequency to the sensor be adjusted for accuracy?

• Two Masses Attached to a Spring [Cunningham, 12/27/2000]
  Two masses are attached to either end of a spring in a gravitational field. One mass is held fixed and the second mass is allowed to hang free and stretch the spring. When the upper mass is released, will the lower mass remain motionless until the spring is in its rest state?

• Voltage Conversion Factors [Coleman, 01/10/2001]
  What are the exact values of the constants for converting among peak, peak-to-peak, rms (root-mean-square) and average voltages?

• Combining Multiple Signals in Data Transmission [Bongers, 02/18/2001]
  How can a cable carry so much information? How can data carriers compress multiple signals and then pull them apart again?

• Center of Mass of a Disk with a Hole [CK, 02/19/2001]
  A circle of radius R with center (0,0) has a smaller circle of radius R/2 and center (R/2,0) removed from its side. Where is the center of mass of the remaining piece?

• Projectile Motion [Gilbert, 02/27/2001]
  If a cannon is firing a cannonball with an initial upward velocity of 100 feet per second, how do you set up a quadratic equation for the projectile motion of the cannonball?

• Jerk - Derivative of Acceleration [Liz, 03/16/2001]
  I need a mathematical term that begins with the letter J, its definition, and a high-school-level explanation of the term.

• How Many Dimensions Are There? [Adam, 03/29/2001]
  How do we know how many dimensions there are? What is the significance of drawing 4D hypercubes? If I were in a 2D world, how would I be able to represent 3D objects?

• Finding the Shape of a Funnel Curve [James, 04/08/2001]
  Find the equation of the curve of revolution of a coin leaving a chute.

• Why is the Universe Black? [Koron, 04/11/2001]
  If a black hole sucks everything into it, wouldn't space be void?

• Combining Ohm's Laws Formulas [Tony, 04/12/2001]
  In electronics, there are two main formulas, V = I*R and P = V*I. How can I combine these to get formulas like P = I^2*R?

• Using Imaginary Numbers [Srini, 05/04/2001]
  Where do we use imaginary numbers in the real world?

• Proof of E = mc^2? [John, 05/04/2001]
  I'm looking for a mathematical proof of E = mc^2. Can you help me fill in the gaps in my proof?

• What is Gravity? [Lewis, 05/06/2001]
  Is gravity caused by the Earth's rotation, or do all objects exert a gravitational pull on each other?

• Absolute Zero [Robert, 05/11/2001]
  Why is absolute zero used in some calculations, e.g. temperature + 460?

• Sextant Theorem [Yolanda, 05/13/2001]
  What mathematical theorem is behind using a sextant, and can it be proved?

• Savings on Gasoline [Janet, 05/22/2001]
  Your old car averaged 22 mpg and you new car should average 37 mpg. Suppose you drive 12,500 miles per year and the cost of gas averages $1.85 per gallon. How much will you save on gasoline each year?

• Speed of Light [Kyrja, 06/08/2001]
  What's m s^-1? Why isn't it just m/s (meters per second) instead? What's the little "-1" at the end?

• Converting mW to dB [Jeff, 06/14/2001]
  I found this equation during a radio receiver discussion: 4x10-12mW = -114dBm. How does it equate?

• Half-Life [Joe, 06/24/2001]
  What is a half-life?

• One equals Two [Dick, 07/25/2001]
  There is an algebraic manipulation involving division by zero that results in one equals two, or some other contradiction. What is it?

• Why Not Meter to the Meter Power? [John, 08/10/2001]
  Why don't we encounter a quantity with dimensions such as m^s or m^m (meter to the power of meter)?

• Exact Weight of One Gallon of Water [Davis, 08/15/2001]
  What is the exact weight of one gallon of water? The best answer I can get is 8.33 or 8.34, depending on the source I go to.

• Negative Entropy in Chemical Reactions [Joseph, 08/20/2001]
  Could you name some chemical reactions in which the disorder of the chemicals involved decreases as a result of the reaction?

• Effective Force Exerted by a Moving Mass [David, 08/23/2001]
  Determine how much force a mass of 1000 lbs. moving at 50 inches/sec will exert on an object in its path about 0.1 inches from where it started (assuming it was moving at the specified velocity throughout the 0.1" distance).

• Stopping Speed and Distance [Adam, 08/28/2001]
  Which can stop faster and/or in a shorter distance - an 18-wheel tractor-trailer or a 2-wheel motorcycle?

• pH Value [Urvashi, 09/05/2001]
  I would like to know the pH value of 0.1 N Sulphuric acid.

• Physics - Acceleration [Nathan, 09/13/2001]
  What equation do you use to find the time element when you have the change in velocity and the displacement?

• Water Level in a Well [Jason, 10/09/2001]
  A man wishes to determine the water level in a deep well. He drops a stone into the well and hears it hit the water 3 seconds later...

• Index of Refraction [Shelby, 10/10/2001]
  How deep is the water in the pool?

• Two Dogs Pulling a Sled [Mike, 10/15/2001]
  What are the magnitude and direction of the force the person will have to exert on the sled to keep it moving along the centerline of the road at constant velocity?

• Electricity: Volts and Amps [Chantal, 10/18/2001]
  How is electricity measured?

• Fourier Transforms [Stuart, 10/19/2001]
  I know what the sinc function is, but I can't convert my expression (in terms of sin) to an expression (in terms of sinc).

• pH Definition [Lily, 10/20/2001]
  What is the 'p' in pH?

• Kinematics - Finding Rocket Height and Speed [Chuck, 10/15/2001]
  During a test a rocket is traveling upward at 75m/s, and when it is 40 m from the ground its engine fails. What is the maximum height reached by the rocket, and what is its speed just before it hits the ground?

• Parsec (pc) [Peter, 10/26/2001]
  One of the unit conversions my Casio fx-991MS calculator does is pc to km and km to pc. What does "pc" mean in this context?

• Size of the Universe [Daniel, 10/31/2001]
  Is it possible to measure the size of the universe?

• Atoms and Molecules [Jenny, 11/28/2001]
  A certain molecule contains twice as many atoms of hydrogen as oxygen and one more atom of carbon than hydrogen. If there are 21 atoms altogether in the molecule, how many atoms of carbon are there?

• Earth's Balance [Thomas, 12/20/2001]
  Why would Earth change its orbit and turning if something as heavy as the Ross Iceshelf moved up some amount of miles?

• Chaos Theory and the Pendulum [Glenn, 12/31/2001]
  How is chaos theory related to physics?

• Falling through the Earth [daren, 12/31/2001]
  If a hole is drilled through the center of the earth to the other side and you jump in, what will happen?

• Math and Makeup [Ashley, 01/05/2002]
  My teacher told us that everything relates to math. I was wondering how makeup relates to math.

• Heisenberg Uncertainty Principle [Darren, 01/01/2002]
  When you look at the Heisenberg Uncertainty Principle, Plank's Constant necomes zero. Is Plank's Constant wrong, or the Uncertainty Principle?

• From What Height Did the Stone Fall? [Brian, 01/30/2002]
  A falling stone takes .30 seconds to travel past a window 2.2m tall. From what height above the top of the window did the stone fall?

• The Feynman Double Slit [Jamshed, 02/01/2002]
  What is quantum mechanics?

• Collision of Two Circular Objects [Alex, 02/02/2002]
  If I have two coins moving across a frictionless surface, knowing their velocity and angles, how can I find the angle of each object after they collide?

• Calculations Involving Significant Figures [Cassandra, 02/22/2002]
  My physics class is having a fair amount of trouble with significant digits.

• Speed of Atoms [Yasser, 02/25/2002]
  What is the speed of the atoms or molecular activity of something as hot as the sun? Will this not be faster than the speed of light?

• Floating Copper Ball [Amber, 02/26/2002]
  Find the wall thickness of a hollow copper ball (sphere) with an outside radius of 50.0 cm that "just floats" in water.

• Relativity and Quantum Theory [Nabi, 03/15/2002]
  What is the problem between relativity and quantum theory that scientists are trying to solve?

• Muzzle Speed [Jaime, 03/21/2002]
  A 15-gram bullet strikes and becomes embedded in a 1.10 kg block of wood placed on a horizontal surface just in front of the gun. If the coefficient of friction between the block and the surface is .25 and the impact drives the block 9.5 meters before it comes to rest, what was the muzzle speed of the bullet?

• Ships and Sea Level [Mark, 03/23/2002]
  How would removing all ships from the ocean affect sea level?

• Centroid - Center of Gravity [Jack, 03/25/2002]
  Can a triangle have a unique centre of gravity?