A box of 100 kg is sliding down along a rough inclined plane of height 2m and length 4m. If coefficient of friction is 0.5 then the force required to be applied so that it comes down with a constant velocity is

The force required to make it fall with a constant velocity is the same as the force due to which it is coming down but in opposite direction. i:e.mgsinθ-μmgcosθ= mgsinθ-μcosθ here sinθ=24=0.5    θ =300100×100.5-0.532=500×0.134=67