Worksheet
Grade 9 Advanced
Problem (1):
A constant force of 10 N is applied to a 2 Kg crate on a rough surface that is sitting on it. The crate
undergoes a frictional force against the force that moves it over the surface.
Assuming the coefficient of friction 0.24
(a) find the magnitude of the friction force that opposes the motion
(b) What is the net force on the crate?
(c) What acceleration does the crate obtain?
Problem (2):
A 75−kg box is pulled over a rough surface using a horizontal force of 100N at a constant velocity.
Find the coefficient of friction between the box and the surface.
Problem (3):
Assume the coefficient of kinetic friction between a 22−kg box and a rough floor is 0.25
(a) What horizontal force is needed for the box to move at a constant speed?
(b) Now, assuming μk=0, what horizontal external force is required?
Problem (4):
A heavy block weighing 300N is moved at a constant speed by a force of 45N applied parallel to the
motion.
(a) What is the coefficient of friction involved in the problem?
(b) What is the mass of the block?
(c) Assuming μk=0, find the acceleration of the block?