~ Onur's n00b questions for Physics

[onur369]

Hey guys, Id like to start off with a question from TSFX trial 2010, Question 2 as attached below, I keep on getting 18000 J whilst the solutions state that it is 32000. I used Fx= 1/2m(v^2-u^2).

[xZero]

Thought tsfx would define g=-9.8ms^-2

anyways using the change in energy, the gravitational potential at the top is E = mgh, E = 50000J. The kinetic energy at the bottom of the track is E = 1/2mv^2, E = 18000J. Since the energy is different, it means that some work (friction) was done on the car, W = E(potential) - E(kinetic), W = 32000J