A small box of mass m 1 is sitting on a board of mass m 2 and length L. The boar
ID: 1321564 • Letter: A
Question
A small box of mass m1 is sitting on a board of mass m2 and length L. The board rests on a frictionless horizontal surface. The coefficient of static friction between the board and the box is ?s. The coefficient of kinetic friction between the board and the box is, as usual, less than ?s. Find Fmin, the constant force with the least magnitude that must be applied to the board in order to pull the board out from under the the box (which will then fall off of the opposite end of the board). Express answer in us, m1, m2, g, and L. Ff should not be included in the answer.
Explanation / Answer
As the system accelerates from the applied force, the box experiences a force against friction equal to m1*a. When that force exceeds the frictional force, the box will slide. Fr =