Question

A block rests on a rough inclined plane making an angle of 30° with horizontal .the coefficient of static friction between the block ond the plane is 0.8 .if frictional force on the block is 30n ,then the mass of the block is (g=10m/s2) ?

Answer 1

From figure , it is clear that the block of mass m , rests on inclined plane due to frictional force .

Hence ,

mgsinθ=f

s

.............eq1

given θ=30

o

,f

s

=10N,g=10m/s

2

Therefore , by eq1

m×10×sin30=10

or m×1/2=1

or m=2kg

Answer 2

From figure , it is clear that the block of mass m , rests on inclined plane due to frictional force .

Hence ,

mgsinθ=f

s

.............eq1

given θ=30

o

,f

s

=10N,g=10m/s

2

Therefore , by eq1

m×10×sin30=10

or m×1/2=1

or m=2kg