Question

lock of mass 10kg is sliding on a surface inclined at a angle of 30o with the horizontal. Calculate the acceleration of the block. The coefficient of kinetic friction between the block and the surface is 0.5

CLASS - XI PHYSICS (Laws of Motion)

Answer 1

a=g[sinθ - μcosθ] Answer: 0.669m/s for g=10

Answer 2

see diagram.
resolve mg = weight of block  in two directions - along the plane and perpendicular to the plane.

    N = mg Cos Ф             as there is no acceleration perpendicular to the incline

    m a = mg Sin Ф - μ N = mg (Sin Φ - μ Cos Φ)
 
       a = g (Sin Φ - μ Cos Φ) = 9.81 (Sin 30 - 0.5 Cos 30)

     acceleration of the block down the plane  = 9.81 (1/2 - 0.5 √3/2)
                = 0.657 meters/sec²