A block of mass 4 kg is placed on a rough horizontal plane. A time dependent horizontal force F = kt acts on the block (k = 2 N/s). Find the frictional force between the block and the plane at t = 2 second and t = 5 second `(mu = 0.2)`

Explanation

When t= 2 sec F = 4N
`f_(ms) = mu_(s) mg = 0.2 xx 4 xx 10 = 8 N`
When t= 5sec F = 2(5) = 10 N
`F gt f, therefore` friction = 8 N