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C HAPTER
5 Forces in Two Dimensions Worksheets
Chapter Outline
5.1 NORMALFORCE ANDFRICTIONFORCE
5.1 Normal Force and Friction Force
Worksheet
Name___________________ Class______________ Date________
Answer each of the questions below to show your achievement of the lesson objectives.
Lesson Objective: Understand how to solve problems involving the normal force.
Use the following prompt for questions #1-5.
Lisa’s mass is 68 kg. She is in an elevator that is moving down and speeding up with an acceleration of -1.5 m/s2 1. Draw a free-body diagram to illustrate all of the forces acting on Lisa.
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11. What is the magnitude and direction of the force due to Earth’s gravity acting on Lisa?
12. What is the magnitude and direction of the net force acting on Lisa?
13. What is the magnitude and direction of the normal force acting on Lisa?
14. In your own words, explain how the forces acting on Lisa are responsible for her motion according to Newton’s laws.
Lesson Objective: Understand how to solve problems involving friction.
Use the following prompt for questions #6-10:
A dog pushes a chew toy with a mass of 3 kg horizontally on the kitchen floor. The coefficient of static friction is 0.8 and the coefficient of kinetic friction is 0.4.
6. What is the normal force acting on the chew toy?
5.1. Normal Force and Friction Force www.ck12.org 7. How much force did it take to get the chew toy to start moving? (Hint: How much force did it take to overcome
the force of static friction?)
8. How much force does it take to get the chew toy to continue sliding across the kitchen floor?
9. Which of the following would help decrease the force of kinetic friction on the chew toy?
a. Pushing down on the chew toy
b. Lifting the chew toy off the floor a little
c. Sliding the chew toy on a carpeted floor (with a coefficient of kinetic friction of 0.8) 10. Explain the reason for your choice above.
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5.2 Inclined Planes
Worksheet
Name___________________ Class______________ Date________
Answer each of the questions below to show your achievement of the lesson objectives.
Lesson Objective: Understand how to analyze and work with forces on inclined planes.
Determine if the following statements are true or false. If false, make the statement true.
1. (True/False) If the weight of a 50 kg box on a flat surface is 500 N, then its weight on an inclined plane will be smaller than 500 N.
2. (True/False) If the weight of a 50kg box on a flat surface is 500 N, then the normal force exerted on it when placed on an inclined plane will be smaller than 500 N.
3. (True/False) The direction of the normal force on an object resting on an inclined plane is always opposing the direction of the force due to gravity.
Use the following prompt for questions #4-7:
A 50 kg box is sliding down a hill with an incline of 30 degrees.
4. What is the weight of the box?
5. What is the horizontal (x) component of the weight of the box?
6. What is the vertical (y) component of the weight of the box?
7. What is the normal force on the box?
Lesson Objective: Understand how to apply Newton’s Second Law to the inclined plane problems.
Use the following prompt for questions #8-10:
A 50 kg box is sliding down a hill with an incline of 30 degrees.
5.2. Inclined Planes www.ck12.org 8. If sliding at a constant speed, what is the force of kinetic friction on the box?
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11. If accelerating at -1 m/s2, what is the force of kinetic friction on the box?
12. If accelerating at -3 m/s2, what is the force of kinetic friction on the box?
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5.3 Circular Motion
Worksheet
Name___________________ Class______________ Date________
Answer each of the questions below to show your achievement of the lesson objectives.
Lesson Objective: Understand that in circular motion there is always an acceleration (and hence a force) that points to the center of the circle defined by the objects motion. This force changes the direction of the velocity vector of the object but not magnitude (the object’s speed).
Use the following prompt for questions #1-5:
The International Space Station orbits the Earth.
1. The centripetal force on the International Space Station is due to a. The force of gravity
b. The force of kinetic friction c. The force of static friction d. The tension force of a rope
2. The direction of the centripetal force on the International Space Station is a. Downward
b. Upward c. Clockwise
d. Toward the center of the circular orbit
3. The direction of the International Space Station’s acceleration is a. Downward
b. Upward c. Clockwise
d. Toward the center of the circular orbit
4. Explain why the International Space Station needed rockets to get into orbit, but doesn’t need rockets to keep it in orbit.
5. Dispel the following misconception: "The astronauts on the International Space Station are floating because there is no gravity in space."
5.3. Circular Motion www.ck12.org Lesson Objective: Understand how to calculate that speed using the period of motion and the distance of its path (circumference of the circle it traces out).
Calculate the magnitude and direction of the centripetal acceleration of the following objects moving in a circle:
6. A 2000 kg truck drives along a circular round a bout with a radius of 20 m at a constant speed of 10 m/s.
7. A 0.08 kg marble moves in a circle with a radius of 0.5 m at a constant speed of 3 m/s.
8. A 64 kg skater travels around a skate rink with a radius of 25 m at a constant speed of 2.2 m/s.
Calculate the speed of the following objects moving in a circle:
9. A 1000 kg racecar drives along a circular track with a radius of 50 m with an acceleration of 4m/s2.
10. A 70 kg runner runs around a track with a radius of 36.8 m with an acceleration of 3 m/s2.
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5.4 Forces in Translational Equilibrium
Worksheet
Name___________________ Class______________ Date________
Answer each of the questions below to show your achievement of the lesson objectives.
Lesson Objective: Understand how to apply Newton’s Second Law under equilibrium conditions in two dimensions.
A 10 kg picture is hanging in static equilibrium on a wall by three wires as depicted below.
Complete the following chart using your understanding of Newton’s Second Law under equilibrium conditions in two dimensions.
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C HAPTER
6 Work and Energy
Worksheets
Chapter Outline
6.1 WORK