Question

Question 5.6 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?

Chapter Laws Of Motion Page 110

Answer 1

We will apply Newton 2nd law of motion,
F = ma
where a = vf - vi / t
Force will be in direction of acceleration as direction is unchanged so it will be in direction of displacement.

Answer 2

Given ,
Mass of body = 3 Kg
Body changes speed 2 m/s to 3.5 m/s in 25 sec .
Hence,
Acceleration = change in vel/time
= ( 3.5 - 2)/25
= 1.5/25 m/s²

Now,
Force = mass of body × acceleration
= 3× 1.5/25
= 4.5/25 N = 0.18 N

Hence, 18 N force acting on body as long the direction of motion of it .