Answer
given,
mass of the block = 78 Kg
coefficient of static friction = 0.2
Ramp is inclined so, assuming the angle of ramp be equal to 40°.
Frictional force = μs N...........(1)
Normal force,
N = m g sin θ
now, putting value of N in equation (1)
f = μs m g sin θ
g is acceleration due to gravity, g = 9.8 m/s²
f = 0.2 x 78 x 9.8 x sin 40°
f = 98.27 N
hence, the frictional force acting between block and ramp is equal to f = 98.27 N