Simple Harmonic Motion 4 Question 13

13. A spring block system is resting on a frictionless floor as shown in the figure. The spring constant is 2.0Nm1 and 1kg2ms12kgmmm the mass of the block is 2.0kg. Ignore the mass of the spring. Initially, the spring is in an unstretched condition. Another block of mass 1.0kg moving with a speed of 2.0ms1 collides elastically with the first block. The collision is such that the 2.0kg block does not hit the wall. The distance, in metres, between the two blocks when the spring returns to its unstretched position for the first time after the collision is

(2018 Adv.)

Analytical & Descriptive Questions

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Answer:

Correct Answer: 13. (2.09)

Solution:

  1. Just Before Collision,

1kg2m/s2kg

Just After Collision

Let velocities of 1kg and 2kg blocks just after collision be v1 and v2 respectively.

From momentum conservation principle,

1×2=1v1+2v2

Collision is elastic. Hence e=1 or relative velocity of separation = relation velocity of approach.

From Eqs. (i) and (ii),

v2v1=2

v2=43m/s,v1=23m/s

2kg block will perform SHM after collision,

t=T2=πmk=3.14s Distance =|v1|t=23×3.14=2.093=2.09m



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