Find velocity of the vehicle:

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

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

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

Sol :

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

As                F = ma

200 = 400 X a

a=0.5m/sec2                                                                                                     ...(i)

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

v = u + at

= 20 + 0.5 X 120

v = 80m/sec                                                                           ........ANS

(2) Velocity of car after 120sec, when force acts in opposite direction of motion.
v = u - at

= 20 - 0.5 X 120

v = -40m/sec                                                    .......ANS

Negative sign indicate that body is moving in the reverse direction