- A flatbed truck is driving
around an unbanked curve that has a radius of 20.0 m. The truck is moving
with a speed of 7.50 m/s. There is a crate on the bed of the truck. What
is the minimum value of the coefficient of static friction between the
crate and the truck bed that is required for the crate not to slide as
the truck goes around the corner?
First let's draw a sketch of the truck's path as seen from above and a free body diagram of the forces acting on the crate.
The centripetal force that makes the crate move in a circular path, is provided by the friction between the truck bed and the crate. So that we can say:
Since the truck bed is horizontal,
and there are no other force with vertical components the normal force
is equal to the weight of the crate which is given by the mass of the grate
multiplied by the acceleration due to gravity. As follows:
So the coefficient of friction
only has to be 0.287 for the crate not to slide.
Return to Example Problems Page