Question

The (non-conservative) force propelling a 2.00 x 103-kg car up a mountain road does 6.80 x 106 J of work on the car. The car starts from rest at sea level and has a speed of 30.0 m/s at an altitude of 1.70 x 102 m above sea level. Obtain the work done on the car by the combined forces of friction and air resistance, both of which are non-conservative forces.

Answer 1

Work done due to propelling force W_PF = 6.8 times 10^6 J Mass = 2 times 10^3 Kg initial velocity , u = 0 M/s final velocity v = 30 M/S Using work - energy theorem w _net = change in K.E W_PF + W _Friction + W _air drag + W _gravity = 0.5 m(v^2 - 0) w _air drag + W _friction = 0.5 times 2 times 10^3 times 30^2 - 6.8 times 10^6 + 2 times 9.8 times 10^3 times 170 W _air drag + w _friction = -2.568 times 10^6 J