Question

A metal ball of mass 2 kg moving with a velocity of 36 km/h has an head on collision with a stationary ball of mass 3 kg. If after the collision, the two balls move together, the loss in kinetic energy due to collision is

• A. 40 J
• B. 60 J
• C. 100 J
• D. 140 J

Answer 1

Answer: (B)

60 J

Answer 2

$v = 36 \mathrm {~km} / \mathrm { h } = 10 \mathrm {~m} / \mathrm { s }$

By law of conservation of momentum

$2 \times 10 = ( 2 + 3 ) V$ ⇒ $V = 4 \mathrm {~m} / \mathrm { s }$

Loss in K.E.