Maximum Acceleration for Crate on Moving Flatbed

[landerson888]

Homework Statement

a flatbed truck is carrying a 20KG crate down a sloping road inclined 15 degrees above the horizontal. The coefficient of static friction between the crate and the bed in 0.400. what is the maximum acceleration that a truck can have if th4 crate is to stay in place?

Homework Equations

The Attempt at a Solution

 

[landerson888]

the crate stays still on a moving flatbed truck

 

[ehild]

What is the acceleration of the crate with respect to the ground?
If there is acceleration, there is a net force of F=ma. What forces act on the crate?

ehild