Q.

A ball of mass 0.5 kg is dropped from a height of 40 m. The ball hits the ground and rises to a height of 10 m. The impulse imparted to the ball during its collision with the ground is (Take g=9.8m/s2)                [2025]
 

1 0  
2 84 NS  
3 21 NS  
4 7 NS  

Ans.

(3)

Mass of ball, m=0.5 kg

h1=40m and h2=10m

So, velocity of ball before hitting the ground

v1=2gh1=2×9.8×40v1=28m/s

After hitting the ground, let final velocity of the ball be v2.

  v2=2gh2=2×9.8×10v2=14m/s

Change in momentum, Δp=m[v2-(-v1)]

=12[14-(-28)]

Δp=21kgImpulse, Δp=21N s