Work Energy And Power Question 107
Question: A steel ball of radius 2 cm is at rest on a frictionless surface. Another ball of radius 4cm moving at a velocity of 81 cm/sec collides elastically with first ball. After collision the smaller ball moves with speed of [RPMT 1999]
Options:
A) 81 cm/sec
B) 63 cm/sec
C) 144 cm/sec
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
Ratio in radius of steel balls = 1/2
So, ratio in their masses $ =\frac{1}{8} $ [As $ M\propto V\propto r^{3} $ ]
Let $ m_1=8m $ and $ m_2=m $
$ v_2=\frac{2m_1u_1}{m_1+m_2}=\frac{2\times 8m\times 81}{8m+m}=144cm/s $
