- #1

JamesL

- 33

- 0

**Problem concerning energy...**

Heres the problem:

A train with total mass of 2.16 x 10^6 kg rises 750 m while traveling a distance of 51.4 km at an average speed of 9.12 m/s. The frictional force is .8 percent of the weight.

Given: acceleration of gravity is 9.8 m/s.

*Find the kinetic energy of the train in MJ.

*Find the total change in its potential energy in J.

*Find the energy dissipated by friction in J.

*Find the power output of the trains engines in MW.

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On the first part i tried using K = .5mv^2, but that is apparently not the way to do it. I am assuming i have to factor in the work done by friction as well?

That brings me to another question. In trying to find the energy dissipated by friction i did the following:

(mass)(.8 percent)(distance) = Work done by friction

(2.16 x 10^6)(.8/100)(51400) = 8.8819 x 10^8

this is not correct either... so I am puzzled as to what I am doing wrong?

Can anyone point me in the right direction for this problem? Thanks!