Equation of motion when the mass slides down Mgsinθ−f=Ma⇒10−f=6(M=2 kg,a=3 m/s2,θ=30∘ given )∴f=4 N { Equation of motion when the block is } pushed up Let the external force required to take the block up the plane with same acceleration be F F−Mgsinθ−f=Ma⇒F−10−4=6F=20 N 