Download Practice Problems – Weight, Normal Force, and Tension Physics

Practice Problems – Weight, Normal Force, and Tension
Physics
For all problems assume air resistance is negligible. You are encouraged to use g = 10 m/s/s for this
activity.
1. (Level 2) A box with a mass of 10 kg is resting on the ground.
a. Draw a free body diagram of the box.
b. What is the net force on the object.
c. Calculate the force due to gravity of the box.
d. Determine the normal force the box feels from the ground.
2. Emily pushes down on a 5 kg box with an applied force of 30 N. The arrow in the drawing to the
right represents this applied force. The box remains at rest the entire time.
Fapp = 30 N
a. Draw a free body diagram of the box.
b. Determine the box’s weight.
c. What is the net force on the box?
d. Determine the normal force on the box.
3. Lata has a string tied around a 20 kg box. He pulls up on the box using the string and exerts a
tension force of 70 N on the box. The box stays at rest on the ground the entire time.
a. Draw a free body diagram of the box.
b. Determine the force due to gravity of the box.
c. What is the acceleration of the box?
d. Calculate the normal force on the box.
4. Gilberto lifts a 3 kg box with an applied force of 36 N, accelerating it upward.
a. Draw a free body diagram of the box.
b. What is the box’s weight?
c. What is the net force on the box?
d. Calculate the acceleration of the box.
5. Eric is lifting weights. He exerts an applied force on a dumbbell that weighs 25 Newtons. It
moves vertically upward with an acceleration of 2 m/s/s.
a. Draw a free body diagram of the dumbbell.
b. Determine the mass of the dumbbell.
c. What is the net force on the dumbbell?
d. What is the applied force on the dumbbell?
Level 4
6. A fisherman yanks a fish vertically out of the water with an acceleration of 2.5 m/s/s using a very
light fishing line that has a breaking strength of 22N. The fisherman loses the fish as the line snaps.
a. Draw a free body diagram of the fish.
b. What is the minimum mass of the fish?
7. A student tugs at a 9.0 kg box using a rope at the angle indicated in the drawing. The box
does not move. The tension in the rope is 72 N.
a. Draw a free body diagram of the box.
b. Determine the normal force the ground exerts on the box.
30°
8. A 20.0 kg box rests on a table. A 5.0 kg box is placed on top of it as shown in the drawing to the
right.
a. Draw a free body diagram of the 20.0 kg box.
b. Draw a separate free body diagram of the 5.0 kg box.
5.0 kg
c. Draw a free body diagram of the system of the two boxes together.
d. Determine the normal force the table exerts on the 20.0 kg box.
20.0 kg
e. Determine the normal force that the 20.0 kg box exerts on the 5.0 kg box.