Do not fill out the information below until instructed to do so! Name: Signature: Student ID: Section Number:

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1 Do not fill out the information below until instructed to do so! Name: Signature: Student ID: Section Number: Formulae are provided on the last page. You may NOT use any other formula sheet. You may use this exam or come up front for scratch paper. Although the questions are multiple-choice all work must be shown to get credit for the answer marked. If the answer marked does not obviously follow from the shown work, even if the answer is correct, you will get zero credit for the answer. The points per question are indicated. Clearly erase any unwanted marks. No credit will be given if we can t figure out which answer you are choosing. Be careful in marking your answer. Because it is multiple-choice format there will be no partial credit. If you mistakenly mark the wrong answer you will get zero credit for the answer. Double check your work and answers before turning them in. Each question is worth 5 points unless otherwise marked. Put your initials here after reading the above instructions (doing so means that you understand and agree with the above instructions):

2 Please read ALL answers. NO CREDIT WILL BE GIVEN IF REASONING AND WORK IS NOT SHOWN. An advertisement claims that a particular automobile can stop on a dime." 1. What net force would actually be necessary to stop a 850 kg automobile traveling initially at 45.0 km/h in a distance equal to the diameter of a dime, which is 1.8 cm? a) 1.06 X 10 9 N b) 1.06 X 10 4 N c) X 10 7 N d) X 10 6 N e) X 10 5 N 2. What is the car's net acceleration? a) X 10 3 m/s 2 b) m/s 2 c) X 10 6 m/s 2 d) -347 m/s 2 e) 5.6 X 10 4 m/s 2 3. How long will it take for the automobile to stop assuming constant acceleration? a) 3.6 X 10-2 s b) 2.9 X 10-3 s c) 1.4 X 10-3 s d) 7.1 X 10-2 s e) 8.0 X 10-4 s

3 Please read ALL answers. NO CREDIT WILL BE GIVEN IF REASONING AND WORK IS NOT SHOWN. A large wrecking ball is held in place by two light steel cables. If the mass of the wrecking ball is 4100 Kg 4. What is the tension T B? a) 2.5 X 10 4 N b) 6.3 X 10 4 N c) 3.0 X 10 4 N d) 4.0 X 10 4 N e) 5.2 X 10 4 N 5. What is the tension T A? a) 5.2 X 10 4 N b) 6.8 X 10 4 N c) 8.2 X 10 4 N d) 4.0 X 10 4 N e) 3.3 X 10 4 N

4 A box of bananas weighing 40.0 N rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.40 and the coefficient of kinetic friction is If no horizontal force is applied to the box and the box is at rest, how large is the friction force exerted on the box? 7. What is the magnitude of the friction force if a monkey applies a horizontal force of 6.0 to the box and the box is initially at rest? 8. What minimum horizontal force must the monkey apply to start the box in motion? 9. What minimum horizontal force must the monkey apply to keep the box moving at constant velocity once it has been started? 10. If the monkey applies a horizontal force of 18.0, what is the magnitude of the friction force?

5 The 4.00 Kg block in the figure is attached to a vertical rod by means of two strings. When the system rotates about the axis of the rod, the strings are extended as shown in the diagram and the tension in the upper string is 75.0 N. 11. What is the tension in the lower cord? a) 75.0 N b) 26.0 N c) 60.0 N d) 39.2 N e) 49.0 N 12. How many revolutions per minute does the system make? a) 33.4 rev/min b) 43.0 rev/min c) 51.3 rev/min d) 29.9 rev/min e) 37.0 rev/min 13. Find the number of revolutions per minute at which the lower cord just goes slack? a) 0.61 rev/min b) 0.71 rev/min c) 52.2 rev/min d) 37.0 rev/min e) 43.0 rev/min

6 14. In terms of m 1, m 2, and g, find the acceleration of the first block in the figure. There is no friction anywhere in the system. a) b) c) d) e) 15. In terms of m 1, m 2, and g, find the acceleration of the second block in the figure. There is no friction anywhere in the system. a) b) c) d) e) 16. In terms of m 1, m 2, and g, find the tension of the cable in the figure. There is no friction anywhere in the system. a) b) c) d) e)

7 17. A nonzero net force acts on an object. Which of the following statements is false: a) It is possible for the particles speed to be constant. b) It is possible for the particle s kinetic energy to be constant. c) It is possible for the particles velocity to be constant. d) It is possible for the particle to move in an opposite direction to the net force e) All of the above 18. (10 points) A 2.8 Kg block slides over the smooth, icy hill shown in the figure. The top of the hill is horizontal and 70 m higher than its base. What minimum speed must the block have at the base of the hill so that it will not fall into the pit on the far side of the hill? a) 30 m/s b) 36 m/s c) 38 m/s d) 42 m/s e) 46 m/s

8 19. A wooden block with mass 1.90 Kg is placed against a compressed spring at the bottom of a slope inclined at an angle of 29.0 degrees (point A). When the spring is released, it projects the block up the incline. At point A, a distance of 5.05 m up the incline from, the block is moving up the incline at a speed of 6.60 m/s and is no longer in contact with the spring. The coefficient of kinetic friction between the block and incline is µ k = The mass of the spring is negligible. Calculate the amount of potential energy that was initially stored in the spring? a) 47.4 J b) 82.5 J c) 93.0 J d) J e) J

9 Formula sheet Vectors The following always apply The following apply for constant acceleration Other equations Some constants Some mathematical formulas: