Name
Period
Date
Net Force (Balanced Forces) Worksheet 7
1. A rollercoaster car, of mass 300. kg with passengers, accelerates down a 50.° hill.
Assume that friction is small enough that it can be ignored.
a. Draw and label all forces (not
b. Draw and label a second force diagram
components) acting on the car and
with all components.
riders.
c. Calculate the component of the
force of gravity acting parallel to the
hill.
d. Write a net force equation for the
parallel forces, and then calculate the
acceleration of the car and riders.
e. If they are traveling 4.0 m
f. Write an equation for the perpendicular
forces acting on the car and riders, and
then calculate the Normal force.
at the
s
time shown in the picture, how fast
will they be traveling at the end of
the straight stretch, 20. m later?
Net Force Worksheet 7
page 2
25
2. A box is allowed to accelerate down a frictionless 25° ramp.
a. Draw and label all of the forces (not b. Draw and label a second force diagram
components) acting on the box.
of the box with all components.
c. Derive a symbolic expression for
the component of the gravitational
force acting down the hill.
e. Compare the normal force to the
force of gravity. Justify with a written
explanation.
d. Write a net force equation for the
parallel force, and then calculate the
acceleration of the block down the
ramp. (You must substitute (c) since
the mass is not given.)
f. How long will it take for the block to
slide 30. m?
Net Force Worksheet 7
page 3
25 N
20.
5.0 kg
3. An applied 25 N force pushes on a 5.0 kg block resting on a frictionless horizontal
surface. The force is directed downwards at an angle of 20.°.
a. Draw and label the forces (not components) acting on the box.
5.0 kg
If you need to draw anything besides what you have shown in part (a) to assist in your
solutions, use the space below. Do NOT add anything to the figure in part (a).
b. Write a net force equation for the
c. Write an equation for the vertical forces
horizontal forces acting on the block,
acting on the block, and then calculate
and then calculate the acceleration
the normal force acting on the block.
of the block.
d. How does the normal force compare to the weight of the box? Justify your
answer both with actual quantities and with a written justification.
Net Force Worksheet 7
page 4
4. A 70. kg box is pulled by a 400. N force at an
angle of 30.° to the horizontal. The force of
kinetic friction is 75 N.
a. Draw and label the forces (not
components) acting on the box.
If you need to draw anything besides what you have shown in part (a) to assist in your
solutions, use the space below. Do NOT add anything to the figure in part (a).
b. What would you
need to know to
decide if the box is
accelerating?
c. Find these quantities
and determine if the box
is accelerating.
d. In what direction is it
accelerating? How do
you know?
e. Write a net force equation for the horizontal forces,
and then calculate the acceleration of the box.
f. What does the
acceleration found in
(e) mean?
g. Write an equation for the vertical
forces acting on the box and
calculate the normal force.
h. What is the coefficient of kinetic friction
between the box and the ground?
Net Force Worksheet 7
page 5
10. kg
20.
5. A 10. kg block is allowed to slide down a ramp with a coefficient of kinetic friction
between the box and the incline of  k  0.15 .
a. Draw and label the forces (not components) acting on the block.
10. kg
If you need to draw anything besides what you have shown in part (a) to assist in your
solutions, use the space below. Do NOT add anything to the figure in part (a).
b. Write an equation for the
perpendicular forces acting on the
box. What is the value of the
normal force acting upon the box?
d. Calculate the parallel
component of the force of
gravity Fgx  acting on the
box.
c. What is the value of the frictional force
opposing the block's slide down the
ramp?
e. Write a net force equation for the parallel forces.
What is the acceleration of the block?