Question

A car of mass 400kg is moving with a velocity of 20m/sec. A force of 200N acts on it for 2 minutes. Find the velocity of the vehicle: 

(i) When the force acts in the direction of motion. 

(ii) When the force acts in the opposite direction of the motion.

Answer 1

m = 400Kg, u = 20m/sec, F = 200N, t = 2min = 120sec, v =?

Since F = ma

200 = 400 X a

a = 0.5m/sec²

(i) Velocity of car after 120sec, When the force acts in the direction of motion

v = u + at

= 20 + 0.5 X 120

v = 80m/sec

(ii) Velocity of car after 120sec, When the force acts in the opposite direction of motion

v = u - at

= 20 - 0.5 X 120

v = -40m/sec

-ve sign indicate that the body is moving in the reverse direction.