Work Energy And Power Question 169
Question: A mass of 20 kg moving with a speed of 10m/s collides with another stationary mass of $ 5kg. $ As a result of the collision, the two masses stick together. The kinetic energy of the composite mass will be [MP PMT 2000]
Options:
A) 600 Joule
B) 800 Joule
C) 1000 Joule
D) 1200 Joule
Show Answer
Answer:
Correct Answer: B
Solution:
$ m_1v_1+m_2v_2=(m_1+m_2){v _{sys\text{.}}} $
$ 20\times 10+5\times 0=(20+5)\ {v _{sys\text{.}}} $
therefore $ {v _{sys\text{.}}}=8m/s $
K.E. of composite mass $ =\frac{1}{2}(20+5)\times {{(8)}^{2}}=800J $
