A ball falls from a height of 5 m and strikes a lift which is moving in the upward direction with a velocity of 1 m s- 1 , then the velocity with which the ball rebounds after collision will be

Question

A ball falls from a height of 5 m and strikes a lift which is moving in the upward direction with a velocity of 1 m s- 1 , then the velocity with which the ball rebounds after collision will be (A) 11 m s- 1 downwards (B) 12 m s- 1 upwards (C) 13 m s- 1 upwards (D) 12 m s- 1 downwards

Tardigrade Admin · Accepted Answer

Velocity after a fall of 5 m is, u1=√2 × 10 × 5=10 m s- 1 <img class="img-fluid question-image" alt="Solution" src="https://cdn.tardigrade.in/q/nta/p-qy93poat4tlm.png" /> ( barv)1-( barv)2=e(( baru)2 - ( baru)1) v1-1=1-(- 10) v1=12 m s- 1

Q. A ball falls from a height of $5 m$ and strikes a lift which is moving in the upward direction with a velocity of $1 m s^{- 1}$ , then the velocity with which the ball rebounds after collision will be

$11 m s^{- 1}$ downwards

$12 m s^{- 1}$ upwards

$13 m s^{- 1}$ upwards

$12 m s^{- 1}$ downwards

Velocity after a fall of $5 m$ is,
$u_{1} = 2 \times 10 \times 5 = 10 m s^{- 1}$

$(\overset{v}{ˉ})_{1} - (\overset{v}{ˉ})_{2} = e ((\overset{u}{ˉ})_{2} - (\overset{u}{ˉ})_{1})$
$v_{1} - 1 = 1 - (- 10)$
$v_{1} = 12 m s^{- 1}$

Q. A ball falls from a height of 5m and strikes a lift which is moving in the upward direction with a velocity of 1ms−1 , then the velocity with which the ball rebounds after collision will be

11ms−1 downwards

12ms−1 upwards

13ms−1 upwards

12ms−1 downwards