A car of mass is moving along a straight horizontal road when the driver applies the…
PHYSICS · Multi-part · CBSE · Physics · Work and Energy · Work and Energy
Problem
A car of mass 1000kg is moving along a straight horizontal road when the driver applies the brakes, producing a constant retarding force of 4000N opposite to the direction of motion. The car finally comes to rest after travelling 50m during braking.
(i) Calculate the work done by the braking force on the car during this distance.
(ii) State whether the work calculated in part (i) is positive, negative or zero and justify your choice.
(iii) If the same braking force were applied but the car covered only 30m before stopping, how much work would the brakes do in this case?
(iv) From your answers, explain quantitatively how the amount of work done by a constant force depends on the displacement when the force is parallel to the displacement.