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C HAPTER
5 Forces in Two Dimensions Assessments
Chapter Outline
5.1 NORMALFORCES ANDFRICTION FORCES
www.ck12.org Chapter 5. Forces in Two Dimensions Assessments
5.1 Normal Forces and Friction Forces
Lesson Quiz
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.
A box with a mass of 10kg is resting on the floor.
1. Draw a free-body diagram to illustrate all the forces acting on the box.
2. What is the magnitude and direction of the force due to Earth’s gravity acting on the box?
3. What is the magnitude and direction of the normal force acting on the box?
4. What is the magnitude and direction of the net force acting on the box?
5. In your own words, explain how the forces acting on the box are responsible for its motion according to Newton’s laws.
6.
7.
Lesson Objective: Understand how to solve problems involving friction.
Use the following prompt for questions #6-10.
A suitcase with a mass of 15kg is being pushed rightward on the airport floor. The coefficient of static friction is 0.8 and the coefficient of kinetic friction is 0.4.
6. What is the weight of the suitcase?
7. What is the normal force acting on the suitcase?
8. How much force did it take to get the suitcase to start moving?
5.1. Normal Forces and Friction Forces www.ck12.org 9. How much force does it take to keep the suitcase moving?
10. Which of the following would help decrease the force of kinetic friction on the suitcase?
a. Pushing down on the suitcase b. Placing a box on top of the suitcase
c. Lifting up on the suitcase off the floor a little
d. Sliding the suitcase on a carpeted floor (with a coefficient of kinetic friction of 0.8)
www.ck12.org Chapter 5. Forces in Two Dimensions Assessments
5.2 Inclined Planes
Lesson Quiz
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.
Use the following prompt for questions #1-4:
A 78kg skateboarder is skating down a hill with an incline of 60 degrees.
1. What is the weight of the skateboarder?
2. What is the horizontal (x) component of the weight of the skateboarder?
3. What is the vertical (y) component of the weight of the skateboarder?
4.
5.
6. What is the normal force on the skateboarder?
Lesson Objective: Understand how to apply Newton’s Second Law to the inclined plane problems.
Use the following prompt for questions #5-6:
A 78kg skateboarder is skating down a hill with an incline of 60 degrees.
5. If the skateboarder is sliding at a constant speed, what is the force of kinetic friction on the skateboarder?
6. If the skateboarder is accelerating at -3 m/s2, want is the force of kinetic friction on the skateboarder?
For questions #7-9, determine the acceleration of the following boxes if they slide down a frictionless inclined plane with an angle of 30 degrees.
7. 5 kg box
5.2. Inclined Planes www.ck12.org 8. 50kg box
9.
10.
11. 500kg box 12.
13.
14. Write a sentence describing your observations regarding the effect of the mass of the box on the acceleration down a 30 degree inclined plane.
www.ck12.org Chapter 5. Forces in Two Dimensions Assessments
5.3 Circular Motion
Lesson Quiz
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 the speed.
1. 1. Dispel the following misconception, “Centripetal force is a new type of force.”
Use the following prompt for questions #2-5:
A tetherball moves in a circle.
2. The centripetal force on the tetherball 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 the rope
3. The direction of the centripetal force on the tetherball is a. Downward
b. Upward c. Clockwise
d. Toward the center of the circle
4. The direction of the tetherball’s acceleration in the horizontal (x) dimension is a. Downward
b. Upward c. Clockwise
d. Toward the center of the circle
5. In your own words, explain how the tetherball can move in a circle at a constant speed and still be accelerating?
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:
5.3. Circular Motion www.ck12.org 6. A 1000kg truck drives along a circular round-a-bout with a radius of 40 m at a constant speed of 15 m/s.
7. A 0.05 kg golf ball moves in a circle with a radius of 0.05 m at a constant speed of 1 m/s.
8. A 60 kg skateboarder travels around a circular ramp with a radius of 10 m at a constant speed of 4.2 m/s.
Calculate the speed of the following objects moving in a circle:
9. A 3000 kg truck drives along a circular path with a radius of 45 m with an acceleration of 5 m/s2.
10. A 75 kg Olympic sprinter runs around a track with a radius of 36.8 m with an acceleration of 7 m/s2.
www.ck12.org Chapter 5. Forces in Two Dimensions Assessments
5.4 Forces in Translational Equilibrium-Statics
Lesson Quiz
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 8kg picture is hanging on a wall by three wires as depicted below.:::
Determine the force of Tension C needed to keep the picture hanging in static equilibrium. Use the chart to help you organize your work.
5.5. Forces in Two Dimensions www.ck12.org
5.5 Forces in Two Dimensions
Chapter Test
Name___________________ Class______________ Date ________
Answer each of the questions below to show your achievement of the lesson objectives.
Use the following prompt for questions #1-5.
Diane picks up a 10 kg box with an upward acceleration of +2 m/s2.:::
1. Draw a free body diagram to illustrate all the forces acting on the box.
2. What is the magnitude and direction of the force due to Earth’s gravity acting on the box?
a. -10 N downward b. +20 N upward c. -100 N downward d. +120 N upward
3. What is the magnitude and direction of the normal force acting on the box?
a. -10 N downward b. +20 N upward c. -100 N downward d. +120 N upward
4. In your own words, explain how the forces acting on the box are responsible for its motion according to Newton’s laws.
Use the following prompt for questions #6-7:
A man (105 kg) pulls on a stuck drawer (0.5 kg). The force of static friction on the drawer is 3.5 N and the force of kinetic friction on the drawer is 2.6 N.:::
6. What is the coefficient of static friction on the drawer?
7. What is the coefficient of kinetic friction on the drawer?
www.ck12.org Chapter 5. Forces in Two Dimensions Assessments A 14lb (6.35kg) bowling ball is sliding down a 5 meter frictionless ramp with an incline of 25 degrees at a
constant speed.:::
8. What is the weight of the bowling ball?
a. 14 lbs b. 6.35 kg c. -26.8 N d. -63.5 N
9. What is the normal force on the bowling ball?
a. -26.8 N b. +26.8 N c. -63.5 N d. +63.5N
10. What is the acceleration of the bowling ball?
a. 0 m/s2 b. 6.35 m/s2 c. 26.8 m/s2 d. 63.5 m/s2
Use the following prompt for questions #11-13:
An Olympic skier of mass 80 kg skies down a slope of 25 degrees with an acceleration of 4.1 m/s2.:::
11. What is the weight of the skier?
a. 80 kg b. -80 N c. 800 kg d. -800N
12. What is the normal force on the skier?
a. +72.5 N b. +725 N c. +80 N d. +800 N
13. What is the force of friction on the skis?
a. +5 N b. +10 N c. +15 N d. +25 N
Use the following prompt for questions #14-16:
A car is driving around a race track.:::
14. The centripetal force on the car is due to a. The force of gravity
b. The force of friction
5.5. Forces in Two Dimensions www.ck12.org c. The normal force
d. The tension force of a rope
15. The direction of the centripetal force on the car is a. Downward
b. Upward c. Clockwise
d. Toward the center of the circular track 16. The direction of the car’s acceleration is
a. Downward b. Upward c. Clockwise
d. Toward the center of the circle
17. Clark Griswold travels in a 1000kg car with his family and can’t get off the round-a-bout, traveling at a constant speed of 11 m/s in a circle with a radius of 35m. Calculate the magnitude and direction of the centripetal acceleration.
Use the following prompt for questions #18-20.
Spiderman (mass=77.3 kg) hangs at rest from two strings of a web. String A has a tension force of 400N and an angle of 45 degrees. String B has a tension force of 565.6N at an angle of 60 degrees.:::
18. Draw a free body diagram illustrating all the forces acting on Spiderman.
19. Use your understanding of Newton’s 2nd Law to prove that the net force in the horizontal (x) dimension is zero.
20. Use your understanding of Newton’s 2nd Law to prove that the net force in the vertical (y) dimension is zero.
www.ck12.org Chapter 6. Work and Energy Assessments
C HAPTER
6 Work and Energy
Assessments
Chapter Outline
6.1 MOMENTUM