Work done on a hill
I have a slight problem. Please comment on the question and solution.
A car of mass 2 Tonnes arrives at a foot of a hill, travelling at a speed of 10m/s and reaches the top of the hill with a speed of 5m/s. The hill is 500m long and rises 1 in 125. If there is a retarding force of 100N, calculate the amount of work done by the engine in getting the car up the hill.
Solution 1: Energy conservation.
I surmised the following:
Initial KE - Work done= PE gained + Final KE (Is this correct?)
Initial KE= 0.5 X 2000 X 100 = 100KJ
PE Gained= 2000 x 10 x 1/125 = 160J
Final KE = .5 X 2000 X 25 = 25KJ
Work Done = (100-160-25)KJ= -85KJ
The PE gained is where is the change in height
Originally Posted by gbenguse78
The work done by the retarding force is the force times the distance the car moves in the direction of the force.
A very belated reply to all your help. As a husband, worker and A levels student you can call me superman. Apologies for the delay in responding. Thanks once again