A 975-kg car accelerates from rest to 26.7 m/s in a distance of 120 m. What is the magnitude of the average net force acting on the car?
A)740 N
B)2900 N
C)91 N
D)1300 N
E)7900 N

Question

Quizplus · Accepted Answer

The work-energy principle states that the work done on an object is equal to its change in kinetic energy. The car's change in kinetic energy is (1/2)mv^2 = (1/2)(975 kg)(26.7 m/s)^2. The work done is also equal to the force times the distance (F*d). Solving for F gives F = (1/2)(975)(26.7)^2 / 120 = 2900 N.

A 975-Kg Car Accelerates from Rest to 26