The coefficient of static friction between the 3.0 kg crate and the 31° incline shown below is 0.300. What is the magnitude of the minimum force, F, that must be applied to the crate perpendicularly to the incline to prevent the crate from sliding down the incline?

Answer 1

Let F be the applied force

[(M*g cos31) + F]*0.300 > M*g*sin31

to prevent sliding. That ensure that the friction force exceeds the weight force component down the slid.

Solve for F, in Newtons

Answer 2

169.2