 Download Presentation To students viewing this on shared drive: answers to problems are in notes box

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1. To students viewing this on shared drive: answers to problems are in notes box below each slide.

2. How much would a 760 kg car weigh on Venus? Mass of Venus: 4.89 x 1024 kg Radius of Venus: 6.05 x 106 m G = 6.67 x 10-11 N m2/kg2

3. For an object being swung from the end of a string in a vertical circle, where in the circular path is the string most likely to break? The string is most likely to break when the object is at the bottom of the circular path.

4. A distance of 6.00 mm separates two particles of equal mass. If the gravitational force between them is 6.80 x 10-4 N, what is the mass of each particle? • G = 6.67 x 10-11 N m2/kg2

5. How does the gravitational force of attraction change between 2 objects if the mass of A triples and the mass of B quadruples? • The force between the two objects will increase by a factor of 12.

6. You can swing a bucket of water around in a vertical circle and the water will not come out of the bucket. What keeps the water in the bucket? Explain. • The water’s inertia keeps it in the bucket. The water resists changes in its motion, so it “wants” to keep moving in a straight line path. Since the bucket follows a curved path, it catches the water before it can fall out of the bucket.

7. If the bottom of the bucket fell out when the bucket was located halfway along the upward side of the circular path, describe the resulting motion of the water. • The water would move in a straight line path in the upward direction. With the bottom of the bucket gone, there is no longer a normal force pushing the water into a circular path.

8. A child twirls a yo-yo about in a horizontal circle. The yo-yo has a mass of 0.30 kg and is attached to a string 0.90 m long. If the speed of the yo-yo is 1.5 revolution per second, a) what tension must exist in the string?b) What is the centripetal acceleration of the yo-yo?

9. Two cars travel around the same curve, car A at twice the speed of car B. Which car experiences the larger acceleration? How much larger? Car A has 4 times the acceleration as B.

10. Two cars travel around the same curved, flat road with the same constant speed. If car A has twice the mass as car B, which car experiences the greater centripetal force? How much larger? Car A has twice the Fc as car B.

11. A 2.5-kg mass is attached to a string 1.5 meter long and swings in a circle parallel to the horizontal. The mass goes around its path once each 0.70 s. Calculate a) the centripetal acceleration of the object, and b) the tension in the string.

12. A car travels at the same constant speed around two curves, curve A having 3 times the radius of curve B. For which of these curves is the car's acceleration larger? How much larger?

13. How would the gravitational force between two objects be affected if the distance between them were reduced by a third? • The force between the objects would increase by a factor of 9.

14. What is the direction of the net force on a car that travels around a flat, circular track with a constant speed? What actually supplies this net force? Toward the center; friction.

15. If Brian (mass = 78.0 kg) weighs himself and finds that he weighs 80.0 pounds, how far away from the surface of the earth is he? • Earth’s mass  5.98 x 1024 kg • Earth’s radius  6.38 x 106 m • G = 6.67 x 10-11 N m2/kg2 • 1 lb. = 4.545 N

16. An astronaut on Mars weighs 200.9 N at the top of Olympus Mons, the tallest mountain in our solar system. If this astronaut weighs 204.1 N at the surface of Mars, what is the height of Olympus Mons? • Mars’ mass  6.43 x 1023 kg • Mars’ radius  3.40 x 106 m • G = 6.67 x 10-11 N m2/kg2

17. A 45.0 kg girl rides a Ferris Wheel that has a diameter of 21.0 m. If the force of the seat on the girl is 388 N at the top of the ride, how fast is the ride going?

18. What is the maximum safe speed for the Ferris Wheel in the previous problem (diameter = 21.0 m)?

19. Seth and Gina ride a roller coaster that has an inverted loop. When they are at the top of the loop, Gina observes that she feels precisely 1/5 as heavy as she normally does. If the radius of the loop is 7.41 m, how fast are they moving?

20. What is the minimum safe speed for the roller coaster in the previous situation? (radius = 7.41 m)

21. How heavy will 68.0 kg Seth feel when they reach the bottom of the vertical loop, if the roller coaster is moving at 15.5 m/s at that point? How many g’s is this?

22. On a scale from 1-10, how ready do you feel for this test? Why isn’t it a 10?