By utility we meanA lead bullet of mass 0.05kg is fired with a velocity of 200ms‾¹ into a block of mass 0.95kg. Given that the lead block can move freely; the final kinetic energy after impact is?

A. 50J
B. 100J
C. 150J
D. 200J

Correct Answer:

Option A = 50J

Explanation

Given

m₁ = 0.05kg, u₁ = 200ms−1, m₂ = 0.95kg

K.E = ¹/₂ mv²
m₁u₁ = v(m₁ + m₂) [law of conversation of momentum]

v = 0.05×2000.05+95 = 10ms−1
K.E = 12(1)102 = 50J