Question

A force changes the velocity of a body of mass 10kg. From 2m/s to 5m/s in 2seconds.

Find:

(a)The initial momentum of the body

(b)The final momentum of the body

(c)The force acting which changes its velocity from 2m/s to 5m/s.

Answer 1

Given mass = 10 kg, initial velocity u = 2 m/s, final velocity v = 5 m /s, t = 2 secs

1) initial momentum p = mu

p = 10 x 2 = 20 kg m/s

2) final momentum p = mv

p = 10 x 5 = 50 kg m/s

Force is given by F = ma where a =( v-u)/t

F = m(v-u)/t

F = 10(5-2)/2 = 15 N