Question

A body is moving in straight line at 20m/s declerates at rate of 4m/s after 25 second its speed will be?

Answer 1

u = 20m/s

v = ?

a = -4m/s2

t = 25 sec

Using the relation-

v = u + at

= 20 - 4(25)

= 20 - 100

= -80

since, velocity cannot be negative in magnitude, therefore, the body will be at rest after 25 seconds.

☺☺

Answer 2

v = u + at

= 20 - 4(25)

= 20 - 100

= -80m/s