Question

A 1500 kg car parking on an incline street at angle θ = 30º.

a) calculate the magnitude of frictional force fs

b) if μs = 0.7 between the tiers and the street. what is the maximum incline angle θ so that the car will not slide down.

Answer 1

A) given
m = 1500 kg
theta = 30 degrees

Normal force acting on the car, N = m*g*cos(30)

The car is at rest.
so, net force acting along the inclined path, Fnet = 0

fs - m*g*sin(theta) = 0

fs = m*g*sin(theta)

= 1500*9.8*sin(30)

= 7350 N <<<<<<<<<------------------------Answer

b) again use, net force acting along the inclined path, Fnet = 0

fs_max - m*g*sin(theta) = 0

fs_max = m*g*sin(theta)

mue_s*N = m*g*sin(theta)

mue_s*m*g*cos(theta) = m*g*sin(theta)

mue_s = sin(theta)/cos(theta)

= tan(theta)

theta = tan^-1(mue_s)

= tan^-1(0.7)

= 35.0 degrees <<<<<<<<<<<---------------------Answer