Name ________________________ Date ____________ Block ______
Problems to Know
1) Three forces act on an object at the same time. F1 = 10N [East], F2 = 20 N [North] and F3 = 15 N [South].
a) What is the net force?
b) What is the equilibrant force?
2) A 2000kg car is parked on a hill that has an incline of 30°.
a) What is the normal force of the car?
b) What is the gravitational force of the car?
c) What is the static frictional force of the car?
3) A 2000kg car is accelerating up a hill that has an incline of 30° at a rate of .78m/s2 .
a) What is the normal force of the car?
b) What is the gravitational force of the car?
c) What is the net force of the car?
4) On takeoff, the propeller of a helicopter exerts a minimum of 8000-N of force on the helicopter, directed
upward at an angle of 65 degrees above the horizontal. The helicopter rises with constant velocity in the
vertical direction while continuing to accelerate in the horizontal direction.
a) What is the weight of the helicopter?
b) What is the horizontal acceleration?
5) A block weighing 300 N is moved at a constant speed over a horizontal surface by a force of 50 N applied
parallel to the surface.
a) What does the “constant speed” tell you about the forces acting on the block?
b) What is the net force of the block?
c) Draw a free body diagram for the block.
d) What is the force friction?
e) What is the mass of the block?
6) A hockey puck has a coefficient of kinetic friction of μk = .25 and the puck feels a normal force (FN) of 10
N. It is also pushed with an applied force of 25N.
a) What is the frictional force that acts on the puck?
b) What is the mass of the puck?
c) What is the net force acting on the puck?
7) Mr. B’s car broke down and he needs some help. You decided to help push. Together y’all apply a
combined force of 250N to get the car to start rolling. Once it starts rolling it’s a lot easier to keep it moving.
Y’all only have to apply a combined force of 100N to keep it rolling. Oh and his car only has a mass of
35kg.
a) What is the coefficient of static friction?
b) What is the coefficient of kinetic friction?
8) After killing the local flying shark you decided to drag the 25 kg beast home to cook. You attach a rope to it
and start dragging with a force of 200N at an angle of 35° above the ground. There is a kinetic coefficient of
friction between the box and the sidewalk of .35.
a) What are the components of the applied force?
b) What is the force of gravity?
c) What is the ΣFy-direction ?
d) What is the normal force?
e) What is the force of kinetic friction?
f) What is the overall acceleration of the shark?
Problems to Know
1) Mr. B’s car broke down and he needs some help. You decided to help push. Together y’all apply a
combined force of 250N to get the car to start rolling. Once it starts rolling it’s a lot easier to keep it moving.
Y’all only have to apply a combined force of 100N to keep it rolling. Oh and his car only has a mass of
35kg.
a. What is the coefficient of static friction? .728
b. What is the coefficient of kinetic friction? .291
2) A 2000kg car is parked on a hill that has an incline of 30°.
a. What is the normal force of the car? 16991.4 N
b. What is the gravitational force of the car? 19620 N
c. What is the static frictional force of the car? 9810 N
3) On takeoff, the propeller of a helicopter exerts a minimum of 8000-N of force on the helicopter, directed
upward at an angle of 65 degrees above the horizontal. The helicopter rises with constant velocity in the
vertical direction while continuing to accelerate in the horizontal direction.
a. What is the weight of the helicopter? 7250.46 N
b. What is the horizontal acceleration? 4.57 m/s2
4) A block weighing 300 N is moved at a constant speed over a horizontal surface by a force of 50 N applied
parallel to the surface.
a. What does the “constant speed” tell you about the forces acting on the block? The forces are balanced.
b. What is the net force of the block? 0 N
c. Draw a free body diagram for the block.
d. What is the coefficient of kinetic friction (μk)? .167
e. What is the mass of the block? 30.58 kg
5) A hockey puck has a coefficient of kinetic friction of μk = .25 and the puck feels a normal force (FN) of 10
N. It is also pushed with an applied force of 25N.
a. What is the frictional force that acts on the puck? 2.5 N
b. What is the mass of the puck? 1.02 kg
c. What is the net force acting on the puck? 22.5 N in the x direction
6) After killing the local flying shark you decided to drag the 25 kg beast home to cook. You attach a rope to it
and start dragging with a force of 200N at an angle of 35° above the ground. There is a kinetic coefficient of
friction between the box and the sidewalk of .35.
a. What are the components of the applied force? Fappy=114.71 N Fappx= 163.83 N
b. What is the force of gravity? 245.25 N
c. What is the ΣFy-direction ? 0 N
d. What is the normal force? 130.55N
e. What is the force of kinetic friction? 45.69N
f. What is the overall acceleration of the shark? 4.72m/s2
7) Three forces act on an object at the same time. F1 = 10N [East], F2 = 20 N [North] and F3 = 15 N [South].
a. What is the net force?
b. What is the equilibrant force?