Work Energy and Power - Result Question 64

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67. 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]

======= ####67. 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]

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/work-energy-and-power/work-energy-and-power—result-question-64.md (a) $140 J$

(b) $100 J$

(c) $60 J$

(d) $40 J$

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Answer:

Correct Answer: 67. (c)

Solution:

  1. (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. $=100-40=60 J$