Q.

Consider two blocks A and B of masses m1 = 10 kg and m2 = 5 kg that are placed on a frictionless table. The block A moves with a constant speed v = 3 m/s towards the block B kept at rest. A spring with spring constant k = 3000 N/m is attached with the block B as shown in the figure. After the collision, suppose that the blocks A and B, along with the spring in constant compression state, move together, then the compression in the spring is, (Neglect the mass of the spring)         [2025]

1 0.2 m  
2 0.4 m  
3 0.1 m  
4 0.3 m  

Ans.

(3)

Conservation of Linear momentum,

m1v1+m2v2=(m1+m2)vcm

vcm 10×310+5  3015=2 m/s 

Conservation of mechanical energy,

12kx2=12(10)(3)2[12(15)(2)2]

 3000x2=9060=30

 x2=303000=1100

 x=110m