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Question: Answered & Verified by Expert
A block of mass 1 kg is dropped on a spring-mass system as shown in the figure. The block travels 100 meters in the air before striking the 3 kg mass. Calculate maximum compression in the spring, if both the blocks move together after the collision. Spring constant of the string k=1.25×106.

PhysicsOscillationsJEE Main
Options:
  • A 2 cm
  • B 4 cm
  • C 8 cm 
  • D 16 cm
Solution:
2779 Upvotes Verified Answer
The correct answer is: 2 cm
The velocity of 1 kg block just before striking

V=2×10×100=205 m s-1

Applying conservation of momentum, the blocks stick after the collision and move with velocity v

Or 1×205=4v

Final velocity v=55 ,

Using energy conservation

KE+PE= const

12×4×552+12k3gk2

=0+12k.x2

x2=4×25×51.25×106+30×301.25×1062

x=201000 m=2 cm

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