Question

A block of mass 1 kg is projected from the lowest point of along the incline and 15 m per second square is the retardation experienced by the block is

Answer 1

The retardation of the block is provided by the forces as follows:

(1) mgsin(x) downward along the inclined plane

(2) force of friction (it is also downward along the inclined plane as it is opposite block's upward motion)

u = coeeficient of static friction, normal force = mgcos(x), angle of inclination = x = 45 degrees. therefore, F = m*a = mgsin(x) + mgcos(x), or, a = 10 / sqrt(2) + 5 / sqr(2) = 15 / sqrt(2)

Answer 2

a block of mass 1 kg is projected from lowest point up along the inclined plane with velocity v so this is very obvious that friction will act on opposite site