Question

Consider two observers moving with respect to each other at a speed v along a straight line. They observe a bock of mass m moving a distance l on a rough surface. The following quantities will be same as observed by the two observers.
(a) kinetic energy of the block at time t
(b) work done by friction
(c) total work done on the block
(d) acceleration of the block.

Answer 1

Acceleration of the block.

Explanation:

If two observers travel at a pace v along a straight line with each other. They observe a bock of mass m travelling on a rough surface at a distance .The block's acceleration will be the same for both observers. The observers respective kinetic energies are different, as the block tends to pass to both the observers at different speeds. The friction work and the total work done on the block are also different from the observers.  

Thus, option (d) is the right answer.

                 

Answer 2

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Option D is correct

hope it help .........