PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics
Problem
A car of mass 1200kg moves on a horizontal road.
(i) The speed of the car increases uniformly from 10ms−1 to 25ms−1 in 5.0s. Calculate the average force developed by the engine during this interval, neglecting resistive forces.
(ii) Observations show that the actual speed variation is better represented by v(t)=10+3t−0.20t2 (in ms−1) for 0≤t≤5s. Determine the instantaneous force acting on the car at t=3.0s.
(iii) Compare the numerical values obtained in parts (i) and (ii) and state briefly why instantaneous force can differ from average force in an accelerated motion.