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Special Relativity [11/1/1996]

Can you please explain Einstein's theory of special relativity to me?

Abstract Index Notation and Tensors [07/15/2002]

I do not entirely understand abstract index notation for tensors. And can you provide an example of how tensors are used in coordinate transformations?

Acceleration around a Corner [09/17/2005]

What is the formula to find out the acceleration of an object going around a corner?

Adjusting Gear Sizes [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?

Anaesthetic Concentration [07/21/2003]

What is the % concentration when you constitute 100ml water with 2.5g of thiopentone?

Anomalous Addition [02/17/1999]

Is it true that sometimes 2 + 2 = 5?

Arterial Branching Calculus [05/28/2003]

In the surgical connection of a small artery to an existing larger artery, attention must be paid to minimising the viscous resistance to the blood flow... Investigate the distance from B of the join and hence the angle of attachment that minimises the resistance to flow.

Atmospherics of a Space Station [11/26/2000]

A cylinder of radius r, filled with a gas of density p, rotates with angular velocity w. What is the pressure a given distance from the axis?

Black Holes [11/12/1997]

Imagine an observer outside a black hole watching someone wearing a clock moving into the black hole...

Center of Mass of a Disk with a Hole [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?

Centroid - Center of Gravity [03/25/2002]

Can a triangle have a unique centre of gravity?

Circular Motion in a Cassette Player [11/7/1995]

The tape in a cassette player passes over the head at 5 cm per second onto a takeup spool of 5 cm diameter. The tape is 0.01 cm thick. Find an expression for the angular speed of the takeup spool at time t seconds. What modelling assumptions do you make?

Conservation of Kinetic Energy [6/8/1996]

A question about the energy conservation formula under a change of reference frame.

Converting Fluid Velocity [09/08/2002]

I have to convert fluid velocity, m^3/s, to linear velocity, m/s, but I don't know how to convert m^3 to m.

Definition of a Tensor [05/20/2001]

Can you supply a definition of a tensor similar to a vector's definition of "any quantity having magnitude and direction"?

Degrees of Freedom [12/17/2002]

What is meant by 'degrees of freedom'?

Digital Compass [08/23/2002]

How does a digital compass work?

Eigenvalues [12/18/1998]

What is an eigenvalue and how is it used?

Explanation of Electrical Impedance [03/26/2004]

We had a speaker blow and I was told that it was because of the impedance. What does that mean?

Exponential Decay [06/09/2005]

Does an exponential decay calculation ever reach zero?

Extraneous Solutions [08/08/2003]

What should an engineer interpret from an equation, or the solutions of that equation, if its solutions prove to be extraneous?

Finding the Shape of a Funnel Curve [04/08/2001]

Find the equation of the curve of revolution of a coin leaving a chute.

Formula for Calculating Work [06/21/2005]

My calculus text defines the formula for work as W = Fd, so the work needed to lift a 500 lb beam 30 feet would be 500 * 30 = 1500 ft-lbs. But don't we really have to exert an upward force greater than 500 lbs in order to get the beam to move?

Galilean Transformations [09/01/99]

Could you please explain to me the basic principles of Galilean transformation, and provide an example?

Gravitational Forces Acting on the Moon [08/27/2005]

Calculations show that the moon orbits the Earth at a distance which is outside of the distance where the gravitational pull of the Earth and sun are equal. If the sun is exerting more pull on the moon, why doesn't it pop out of Earth orbit and orbit the sun instead?

Heisenberg Uncertainty Principle [01/01/2002]

When you look at the Heisenberg Uncertainty Principle, Plank's Constant becomes zero. Is Plank's Constant wrong, or the Uncertainty Principle?

Mixing Coffee and Milk: Ph and Buffers [07/10/2003]

If I mix coffee (pH 5) and milk (pH 6.9) (50%/50%), what will be the pH of the coffee/milk mixture?

Monkey Climbing a Chain [09/22/1999]

A 20-lb. monkey is attached to a 50-ft. chain that weighs 0.5 lb. per (linear) foot...

Nyquist Frequency Criteria [08/04/2003]

Why do we need two points or samples per cycle to define a frequency component in the original data?

Parallel and Series-Parallel Resistance [05/24/2000]

How do you find the total resistance of resistors in parallel or in series-parallel?

Period of Small Oscillation [08/21/2003]

A square trapdoor, modelled by a uniform rigid lamina of side b and mass 5m, is smoothly hinged at one horizontal edge and has a catch of mass m in the centre of the opposite edge. Find the trapdoor's period of small oscillation about downward hanging equilibrium.

Physics and a Balloon in a Car [06/09/2005]

Consider a balloon filled with helium, hanging from the floor of a car. The car is sealed, and is full of air at ambient surface pressure. If the car undergoes constant acceleration forwards only, which way, relative to the car, will the balloon move?

The Physics of a Horse Pulling a Carriage [07/13/2005]

I'm trying to understand how Newton's Law works with regard to the forces that allow a horse to pull a carriage. How does that work?

The Physics of Baseball [07/11/2000]

How does a baseball move when it is pitched?

Polarized Tensors [04/30/2003]

What is a polarized tensor, and how can we prove that it has rank two? With a list of relevant books on the subject of mathematical tensors.

Quaternion Numbers in Quantum Physics [04/11/2001]

Are there any applications of quaternion numbers in quantum physics?

Rainfall on a Moving Object [09/10/2002]

I would like to figure out the relation between a moving object (a person) and the amount of rain that will hit him given a fixed distance.

Rain - Run or Walk? [08/05/2003]

Is there an optimum speed at which to walk through the rain to minimise the number of drops you get hit by?

Range of the Coefficient of Friction [10/18/2000]

Can the coefficient of friction be greater than one?

Relativity [05/22/2002]

How do you demonstrate algebraically that [the following expressions] are proportional to each other even when they describe 'events' that are not on the expanding wavefront of light?

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