Question

A 1281-kg car is moving due east with an initial speed of 27.9 m/s. After 7.44 s the car has slowed down to 16.8 m/s. Find the magnitude and direction of the net force that produces the deceleration.

magnitude N

direction ---Select---

Answer 1

Acceleration produced : a = Rate of change in velocity = ( Final speed - Initial speed ) / Time taken

or, a = ( 16.8 m / s - 27.9 m / s ) / 7.44 s ~ - 1.5 m / s².

Hence, deceleration produced = d = 1.5 m / s².

Mass of the car = m = 1281 kg.

Hence, magnitude of force applied = F = m x d = 1281 kg x 1.5 m / s² = 1921.5 Newton.

Since the force reduced the speed of the car, this force must be an opposing force, i.e., direction of application of the force is opposite to that of the motion of the car.

Hence, direction of the force is towards west.