PHYSICS · Multi-part · CBSE · Physics · Force and Laws of Motion · Force and Laws of Motion
Problem
A car of mass 800kg slows down uniformly from 15m s−1 to 5m s−1.
(i) Starting from the definition of linear momentum, derive an expression for the average resultant force acting on a body in terms of its mass, change in velocity, and the time taken for the change.
(ii) Using your expression, calculate the average braking force if the speed change described occurs in 4.0s.
(iii) If the same reduction in speed is achieved in 8.0s, determine the new average braking force and state the percentage decrease compared with the value found in part (ii).