Work and Energy ProblemDate: 5/14/96 at 17:10:1 From: Anonymous Subject: Work and Energy Problem I am a junior in a senior Math Analysis class in High School. We are working on Work and Energy problems in Integral Calculus. However, our teacher told us not to use calculus for these problems. Instead we should use the formula: Work = |F||d|cosO (theta) where theta is the angle betwee F and d. I'm having a problem trying to figure out exactly how to do this. I can't seem to find what angle I should use or what to plug in where. Please help! Question: The mass of a loaded helicopter is 1500kg. How much energy does its engine expend in ascending vertically for 120m? Thanks a lot. Date: 11/12/96 at 21:46:24 From: Doctor Robert Subject: Re: Work and Energy Problem In this case the angle between the force vector and the displacement vector is zero degrees. The cosine of zero is 1 so the formula becomes: W = F times d = 1500 kg times 9.8 nt/kg times 120 m = 1.764 x 10^6 joules In a different type of problem, one might have the displacement vector in a different direction from the force vector. A simple example of this is pulling a box along the floor by attaching a rope to it so that the rope makes an angle of 60 degrees above the horizontal. In this case the displacement is horizontal, but the force is not. -Doctor Robert, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
Search the Dr. Math Library: |
[Privacy Policy] [Terms of Use]
Ask Dr. Math^{TM}
© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/dr.math/