Question

A ball of mass $1$ $kg$ drops vertically on to the floor with a speed of $25$ $m/s$ . It rebounds with an initial velocity of $10$ $m/s$ . What impulse acts on the ball during contact?

• A. $35$ $kgm/s$ downwards
• B. $35$ $kgm/s$ upwards
• C. $30$ $kgm/s$ downwards
• D. $30$ $kgm/s$ upwards

Answer 1

Answer: (A)

$35$ $kgm/s$ downwards

Given,

mass of ball is $1kg$

Initial velocity is $10m/s$

Final velocity is $-25m/s$ (Rebounds)

We know that impulse is change in momentum therefore,

$△P=m(v_f-v_i)$

Substitute all value in above equation we will get

$△P=1\times (-25-10)△P=-35m/s$

Here, we have taken in upward direction as positive velocity and in downward direction is as negative velocity therefore, Impulse will act in downward direction with magnitude is $35kgm/s$ hence, correct option is $\left(A\right)$