Civil Engineering - UPSC Civil Service Exam Questions - Discussion

Discussion Forum : UPSC Civil Service Exam Questions - Section 20 (Q.No. 38)
38.
Two spheres of mass 15 kg and 20 kg, move along a straight line in the same direction with velocities of 20 m/s and 5 m/s, respectively. If the coefficient of restitution is 0.7, then the velocity of the 15 kg mass after collision will be
5.43 m/s
15.93 m/s
18.72 m/s
16.16 m/s
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
1 comments Page 1 of 1.

Santu naskar said:   8 years ago
Accoring to law of conservation m1u1+m2u2 = m1v1+m2v2.
Then 15v1+20v2=15*20+20*5 or 3v1+4v2 = 80.
Another eqn from co efficient of restitution v2-v1 = e(u1-u2) or v2-v1=0.7(20-5)=10.5 Or v2-v1=10.5.

Solving two eqn v1=5.43 & v2=15.93 m/s.
(1)

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