Question

A block of mass m is placed on another block of mass M. Here M = 30 kg. m = 10 kg, and u = 0.5 and
there is no friction between the ground and M. At t=0 a force F = 400 N starts acting on M. Calculate the
work done by friction force on block m in the time interval of 2s as seen by (i) observer 1, (ii) observer 2.
Observer 1
M
Observer 2
my
M
ho​

Answer 1

Answer:

According to Newton's third law ; so same amount of friction acts on box m as =force acting upon it