Work Energy And Power Ques 64
64. A metal ball of mass $2$ $kg$ moving with a velocity of $36 $ $km / h$ has a 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
[1997]
(a) $140 $ $J$
(b) $100 $ $J$
(c) $60 $ $J$
(d) $40 $ $J$
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Answer:
Correct Answer: 64.(c)
Solution:
- (c) Applying conservation of momentum, $m_1 v_1=(m_1+m_2) v$
$v=\frac{m_1 v_1}{(m_1+m_2)}$
Here, $v_1=36 $ $km / hr=10 $ $m / s$
$m_1=2 $ $kg, m_2=3$ $ kg$
$v=\frac{10 \times 2}{5}=4 $ $m / s$
K.E. $($ initial $) =\frac{1}{2} \times 2 \times(10)^{2}=100 $ $J$
K.E. $($ Final $)=\frac{1}{2} \times(3+2) \times(4)^{2}=40 $ $J$
Loss in K.E. $=100-40=60 $ $J$
BETA
