A truck is moving at 15m/s when the brakes are applied, in order to come to a stop before hitting a pothole 20m ahead. In the back of the truck is a crate. It is not tied down, but has a coefficient of static friction μs = 0.4 with the truck bed. Will the truck be able to stop in time, without the crate sliding? 1) Draw a pictorial representation of the problem. 2) Choose a coordinate system. Remember to identify where the origin is. 3) List given information as consistent with your chosen coordinates.
A truck is moving at 15m/s when the brakes are applied, in order to come to a stop before hitting a pothole 20m ahead. In the back of the truck is a crate. It is not tied down, but has a coefficient of static friction μs = 0.4 with the truck bed. Will the truck be able to stop in time, without the crate sliding?
1) Draw a pictorial representation of the problem.
2) Choose a coordinate system. Remember to identify where the origin is.
3) List given information as consistent with your chosen coordinates.
4) Static friction problems of the “will it slide” type are usually done in three steps. The first, is to assume the object does not slide. How will you express this condition? That is, what equation must be true if the crate doesn’t slide, and false if it does? (Hint: This relates to acceleration.)
5) Second, one solves for the strength of the static friction based on the assumption of no sliding. Draw a free body diagram for the crate.
6) Construct the Newton’s Second Law equation for the crate, and solve for the magnitude of the static friction force.
7) Third, one compares the required static friction force to the maximum possible static friction force. Compute that maximum static friction force here, and compare to your value from #6.
Trending now
This is a popular solution!
Step by step
Solved in 2 steps with 2 images
