Physics-
General
Easy
Question
A set of
identical cubical blocks lies at rest parallel to each other along a line on a smooth horizontal surface. The separation between the near surfaces of any two adjacent blocks is
. The block at one end is given a speed
towards the next one at time
. All collision are completely elastic. Then

- The last block starts moving at time
- The last block starts moving at time
- The centre of mass of the system will have a final speed
- The centre of mass of the system will have a final speed
The correct answer is: The centre of mass of the system will have a final speed 
Time taken by first block to reach second block 
Since collision is 100% elastic, now first block comes to rest and 2nd block starts moving towards the 3rd block with a velocity
and takes time
to reach 3rd block and so on
Total time
time 
Finally only the last
th block is in motion velocity
, hence final velocity of centre of mass

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