Question

A body of mass 10 kg initially moving with speed 5 ms⁻¹ changes its speed to 25 ms⁻¹ in 4 sec. Calculate the change in momentum and hence force applied.

Answer 1

Change in momentum is equal to 200 Kg m/s and force is equal to 50 N.

Mass of the body = 10Kg

v1 = initial speed = 5 m/s

v2 = final speed = 25 m/s

t = time taken = 4 seconds

a = acceleration of the body

Using [v = u + at] to find the acceleration of the body

v = v2 , u= v1

v2 = v1 + at

=> 25= 5+ a×4

=> 20 = 4a

=> a = 5 m/s²

Force applied = m × a

=> 10 × 5

=> 50 N

Initial momentum of the body = mv1 = 10 × 5

=> 50 Kg m/s

Final momentum of the body = mv2 = 10 × 25

=> 250 Kg m/s

Change in momentum of the body = final momentum-initial momentum

=> 250 - 50

=> 200 Kg m/s