Self-Test: Circular Motion Test #2
Suggested Time: 75 minutes

1.

A 2.5 kg object moves at a constant speed of 8.0 m/s in a 5.0 m radius circle. What is the objects acceleration?

 A. 0 m/s2 B. 1.6 m/s2 C. 13 m/s2 D. 32 m/s2

2.

A satellite moves in a circular path at a constant speed. Which vector in the diagram below best represents the satellites acceleration? A. I B. II C. III D. IV

3. An empty 12 kg seat on a swing-type ride at the fairgrounds has a kinetic energy of 480 J. What is the centripetal force on the empty seat?

 A. 1.2 ´102 N B. 1. 4 ´102 N C. 8.2 ´102 N D. 5.8 ´103 N

4. A small toy airplane suspended as shown below flies in a circular path. Which of the following free body diagrams best describes the forces acting on the airplane at the position shown?

 A. B. C. D. 5.

A 1.5 kg object is in uniform circular motion with a period of 3.0 s. If the radius of the path is 4.0 m, what is the centripetal force on the object?

 A. 18 N B. 26 N C. 41 N D. 59 n

6.

A 75 kg person rides a Ferris wheel which is rotating uniformly. The centripetal force acting on the person is 45 N. What force does the seat exert on the rider at the top and at the bottom of the ride? 7. A ball attached to a string is swung in a horizontal circle. Which path will the ball follow at the instant the string breaks?

 A. I B. II C. III D. IV

8.

A test tube rotates in a centrifuge with a period of 1.20 ´10-3 s . The bottom of the test tube travels in a circular path of radius 0.150 m. What is the centripetal force exerted on a 2.00 ´10-8 kg amoeba at the bottom of the tube?

 A. 9.86 ´10-5 N B. 2.08 ´10-3 N C. 8.22 ´10-2 N D. 4.11´106 N

9.

A physics student swings a 5.0 kg pail of water in a vertical circle of radius 1.3 m. What is the minimum speed, v, at the top of the circle if the water is not to spill from the pail?

 A. 3.6 m/s B. 6.1 m/s C. 8.0 m/s D. 9.8 m/s

10.

In a popular amusement park ride, a large cylinder is set in rotation. The floor then drops away leaving the riders suspended against the wall in a vertical position as shown. Which of the following is the correct free-body diagram for the person at the position shown?

 A. B. C. D. 11.

An object is attached to a string that can withstand a maximum tension force of 6.3 N. The object travels in a circular path of radius 0.40 m with a period of 2.1 s. What is the maximum mass of the object?

 A. 0.57 kg B. 0.64 kg C. 1.8 kg D. 3.6 kg

12. A 1.2 kg mass on the end of a string is rotated in a vertical circle of radius 0.85 m. If the speed of the mass at the top of the circle is 3.6 m/s, what is the tension in the string at this location?

 A. 6.5 N B. 12 N C. 18 N D. 30 N

13.

A 65 kg pilot in a stunt plane performs a vertical loop with a 700 m radius. The plane reaches a speed of 210 m s at the bottom of the loop. What is the upward force on the pilot at the bottom of the loop?

 A. 640 N B. 3500 N C. 4100 N D. 4700 N

14.

An object travels along a circular path with a constant speed v when a force F acts on it. How large a force is required for this object to travel along the same path at twice the speed (2v)?

 A. 1/2 F B.  F C. 2 F D. 4 F

15.

The diagram shows an object of mass 3.0 kg travelling in a circular path of radius 1.2 m while suspended by a piece of string of length 1.9 m. What is the centripetal force on the mass? A. 19 N B. 2 N C. 24 N D. 29 N

16.

A frictionless 3.0 kg cart rolls down an incline, and then "loops the loop." From what minimum height, h, should the cart be released so that it does not fall off the circular track?

 A. 12.0 m B. 15.0 m C. 18.0 m D. 24.0 m

17. A crate of eggs is located in the middle of the flatbed of a pickup truck as the truck negotiates an unbanked curve in the road. The curve may be regarded as an arc of a circle of radius 39.0 m. If the coefficient of static friction between the truck and the crate is 0.625, how fast can the truck be moving without the crate sliding?

18.   Tarzan, whose mass is 85 kg, tries to cross a river by swinging from a vine. The vine is 10.0 m long, and his speed at the bottom of the swing (as he just clears the water) is 8.00 m/s. Tarzan doesn't know that the vine has a breaking strength of  1000 N. Does he make it safely across the water? 19. An amusement park ride consists of a rotating circular platform 8.00 m in diameter from which 10.0 kg seats are suspended at the end of 2.50 m massless chains. When the system rotates, the chains make an angle of q = 28.0? with the vertical. (a) What is the speed of each seat? (b) Find the tension in the chain when a 40.0 kg child is riding in a seat.

20. An 1700 kg car passes over a bump in a road that follows the arc of a circle of radius 40.0 m as shown below. (a) What force does the road exert on the car as the car passes the highest part of the bump if the car travels at 18.0 m/s? (b) What is the maximum speed the car can have if it passes the highest point before losing contact with the road?

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