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Lots of fun! Win valuable prizes!. 1.The reason padded dashboards are used in cars is that they A. look nice and feel good. B. decrease the impulse in.

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Presentation on theme: "Lots of fun! Win valuable prizes!. 1.The reason padded dashboards are used in cars is that they A. look nice and feel good. B. decrease the impulse in."— Presentation transcript:

1 Lots of fun! Win valuable prizes!

2 1.The reason padded dashboards are used in cars is that they A. look nice and feel good. B. decrease the impulse in a collision. C. increase the force of impact in a collision. D. decrease the momentum of a collision. E. increase the time of impact in a collision.

3 2. Momentum of a system is conserved only when A. there are no internal forces acting on the system. B. the system is not moving. C. there are no forces acting on the system. D. there is no net external force acting on the system. E. the system has zero momentum.

4 3. Suppose a girl is standing on a pond where there is no friction between her feet and the ice. In order to get off the ice, she can A. bend over touching the ice in front of her and then bring her feet to her hands. B. walk very slowly on tiptoe. C. get on her hands and knees and crawl off the ice. D. throw something in the direction opposite to the way she wants to go. E. all of the above will work

5 4. Which of the following has the largest momentum? A. A large truck parked in a parking lot B. A tightrope walker crossing Niagara Falls C. Howard High School D. A pickup truck traveling down the highway E. A dog running down the street

6 5. The driver of a 2,500-kg SUV is traveling at 29 m/s while texting on her phone. She looks up to find she is headed straight for a cornfield. If the force of friction between the corn and the SUV is 1,300 N, how long does it take her to stop? (Ignore other sources of friction.)

7 6. A freight train rolls along a track with considerable momentum. If it were to roll at the same speed but had twice as much mass, its momentum would be A. zero. B. unchanged. C. quadrupled. D. doubled.

8 7. A cannon fires a cannonball. The speed of the cannonball will be the same as the speed of the recoiling cannon A. if the mass of the cannonball equals the mass of the cannon. B. because momentum is conserved. C. because velocity is conserved. D. because both velocity and momentum are conserved. E. none of the above

9 8. Recoil is noticeable if you throw a heavy ball while standing on roller skates. If instead you go through the motions of throwing the ball but hold onto it, your net recoil velocity will be A. small but noticeable. B. the same as before. C. zero.

10 9. A karate expert executes a swift blow and splits a cement block with her bare hand. A. The forces on both the block and the expert's hand have the same magnitude. B. The times of impact on both the block and the expert's hand are the same. C. The impulses on both the block and the expert's hand have the same magnitude. D. all of the above E. none of the above

11 10. A sumo wrestler with mass of 150 kg leaps from a bus onto an apple cart at rest. If the bus was traveling at 17 m/s west just before the leap and the velocity of the applecart and wrestler together is 6.3 m/s just after the wrestler lands, what is the apple cart’s mass?

12 11. A moving freight car runs into an identical car at rest on the track. The cars couple together. Compared to the velocity of the first car before the collision, the velocity of the combined cars after the collision is A. zero. B. one half as large. C. the same. D. twice as large. E. More information is needed to say.

13 12. Wile E. Coyote is chasing the Roadrunner while coasting on roller skates at 21 m/s. He lights a rocket on his back, which boosts his velocity to 98 m/s before it burns out 5.5 seconds later. If Wile E. and his gear have a combined mass of 68 kg, what was the average force exerted by the rocket?

14 13. Suppose an astronaut in outer space wishes to toss a ball against a very massive and perfectly elastic concrete wall and catch it as it bounces back. If the ball is as massive as the astronaut, then A. the astronaut's time between catches will decrease as the game progresses. B. the astronaut will never catch the first bounce. C. the astronaut will catch one bounce only. D. none of the above

15 14. Superman is at rest in space when he throws an asteroid that has more mass than he does. Which moves faster, Superman or the asteroid? A. Superman B. The asteroid C. They both move at the same speed.

16 15. A cannonball shot from a long-barrel cannon travels faster than one shot from a short-barrel cannon because the cannonball receives a greater A. force. B. impulse. C. both A and B D. neither A nor B

17 16. An object weighs 20 N on the earth's surface. What is the weight of the object on a planet that has twice the earth's mass and four times the earth's radius? A. 1 N B. 2 N C. 5 N D. 10 N E. 20 N

18 17. What is the gravitational force acting on a 7.5 x kg oil tanker due to a 4.4 x kg iceberg floating 672 m away?

19 Bonus question time!

20 Bonus question Romeo throws a bouquet of roses to Juliet standing on a balcony above. Romeo throws the flowers with a velocity of 11 m/s and an angle of 75° to the horizontal. The bouquet lands on the balcony 1.3 s later. A. What is the horizontal distance from Romeo to the base of the balcony? B. How high is the balcony above Romeo’s outstretched arm?


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