Question
Question: A sphere of mass 0.1 kg is attached to a cord of 1m length. Starting from the height of its point of...
A sphere of mass 0.1 kg is attached to a cord of 1m length. Starting from the height of its point of suspension this sphere hits a block of same mass at rest on a frictionless table, If the impact is elastic, then the kinetic energy of the block after the collision is
A
1 J
B
10 J
C
0.1 J
D
0.5 J
Answer
1 J
Explanation
Solution
As two blocks are of same mass and the collision is perfectly elastic therefore their velocities gets interchanged i.e. the block A comes into rest and complete kinetic energy transferred to block B.
Now kinetic energy of block B after collision = Kinetic energy of block A before collision
= Potential energy of block A at the original height
= mgh = 0.1 × 10 × 1 = 1 J.