1. The three forces shown all have the same magnitude: F a = F b = F c. Which force produces the greatest torque about the point O (marked by the red dot)? 1. the force F a 2. the force F b 3. the force F c 4. not enough information given to decide Q10.1

2. The three forces shown all have the same magnitude: F a = F b = F c. Which force produces the greatest torque about the point O (marked by the red dot)? 1. the force F a 2. the force F b 3. the force F c 4. not enough information given to decide A10.1

3. In which of the situation(s) shown here does the force produce a torque about O that is directed into the plane of the drawing? 1. situation (i) 2. situation (ii) 3. situation (iii) 4. situation (iv) 5. more than one of the above Q10.2

4. In which of the situation(s) shown here does the force produce a torque about O that is directed into the plane of the drawing? 1. situation (i) 2. situation (ii) 3. situation (iii) 4. situation (iv) 5. more than one of the above A10.2

5. A plumber pushes straight down on the end of a long wrench as shown. What is the magnitude of the torque he applies about point O? 1. (0.80 m)(900 N)sin 19° 2. (0.80 m)(900 N)cos 19° 3. (0.80 m)(900 N)tan 19° 4. none of the above Q10.3

6. A plumber pushes straight down on the end of a long wrench as shown. What is the magnitude of the torque he applies about point O? 1. (0.80 m)(900 N)sin 19° 2. (0.80 m)(900 N)cos 19° 3. (0.80 m)(900 N)tan 19° 4. none of the above A10.3

7. 1. m 2 g = T 2 = T 1 2. m 2 g > T 2 = T 1 3. m 2 g > T 2 > T 1 4. m 2 g = T 2 > T 1 5. none of the above Q10.4 A glider of mass m 1 slides without friction on a horizontal air track. It is connected to an object of mass m 2 by a massless string. The string turns the pulley without slipping or stretching. If the glider and object are released, the glider accelerates to the right and the object accelerates downward. During this motion, what is the relationship among T 1 (the tension in the horizontal part of the string), T 2 (the tension in the vertical part of the string), and the weight m 2 g of the object?

8. 1. m 2 g = T 2 = T 1 2. m 2 g > T 2 = T 1 3. m 2 g > T 2 > T 1 4. m 2 g = T 2 > T 1 5. none of the above A10.4 A glider of mass m 1 slides without friction on a horizontal air track. It is connected to an object of mass m 2 by a massless string. The string turns the pulley without slipping or stretching. If the glider and object are released, the glider accelerates to the right and the object accelerates downward. During this motion, what is the relationship among T 1 (the tension in the horizontal part of the string), T 2 (the tension in the vertical part of the string), and the weight m 2 g of the object?

9. A string is wrapped several times around the rim of a small hoop. (The weight of the string is negligibly small compared to the weight of the hoop.) 1. T = w 2. T > w 3. T < w 4. not enough information given to decide Q10.5 If the free end of the string is held in place and the hoop is released from rest, the string unwinds and the hoop descends. As the hoop descends, how does the tension in the string (magnitude T) compare to the weight of the hoop (w)?

10. A string is wrapped several times around the rim of a small hoop. (The weight of the string is negligibly small compared to the weight of the hoop.) 1. T = w 2. T > w 3. T < w 4. not enough information given to decide A10.5 If the free end of the string is held in place and the hoop is released from rest, the string unwinds and the hoop descends. As the hoop descends, how does the tension in the string (magnitude T) compare to the weight of the hoop (w)?

11. A solid bowling ball rolls down a ramp. Which of the following forces exerts a torque on the bowling ball about its center? 1. the weight of the ball 2. the normal force exerted by the ramp 3. the friction force exerted by the ramp 4. more than one of the above 5. answer depends on whether or not the ball is rolling without slipping Q10.6

12. A solid bowling ball rolls down a ramp. Which of the following forces exerts a torque on the bowling ball about its center? 1. the weight of the ball 2. the normal force exerted by the ramp 3. the friction force exerted by the ramp 4. more than one of the above 5. answer depends on whether or not the ball is rolling without slipping A10.6

13. A yo-yo is placed on a horizontal surface as shown. There is sufficient friction for the yo-yo to roll without slipping. If the string is pulled to the right as shown, 1. the yo-yo rolls to the right 2. the yo-yo rolls to the left 3. the yo-yo remains at rest 4. answer depends on the magnitude F of the pulling force compared to the magnitude of the friction force Q10.7

14. A yo-yo is placed on a horizontal surface as shown. There is sufficient friction for the yo-yo to roll without slipping. If the string is pulled to the right as shown, 1. the yo-yo rolls to the right 2. the yo-yo rolls to the left 3. the yo-yo remains at rest 4. answer depends on the magnitude F of the pulling force compared to the magnitude of the friction force A10.7

15. A spinning figure skater pulls his arms in as he rotates on the ice. As he pulls his arms in, 1. his angular momentum increases 2. his angular momentum remains the same 3. his angular momentum decreases 4. answer depends on how far he pulls his arms in Q10.8

16. A spinning figure skater pulls his arms in as he rotates on the ice. As he pulls his arms in, 1. his angular momentum increases 2. his angular momentum remains the same 3. his angular momentum decreases 4. answer depends on how far he pulls his arms in A10.8