Question

A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 m s^–1 to 3.5 m s^–1 in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force?

Answer 1

0.18 N; in the direction of motion of the body
Mass of the body, m = 3 kg
Initial speed of the body, u = 2 m/s
Final speed of the body, v = 3.5 m/s
Time, t = 25 s

Using the first equation of motion, the acceleration (a) produced in the body can be calculated as: v = u + at

As per Newton’s second law of motion, force is given as:
F = ma
= 3x0.06 = 0.18 N

Since the application of force does not change the direction of the body, the net force acting on the body is in the direction of its motion.