1. Determine his speed when he reaches the photo radar car.

Transcription

1 Physics Unit Review 5 Use the following information to answer the next two questions. Mr. Buffi is cruising at 18.9 m/s when he sees a suspicious car (perhaps a photo radar car?) parked on the side of the street. He changes his speed at m/s 2. He passes the parked car in 1.50 s. 1. Determine his speed when he reaches the photo radar car. 2. If the speed limit is 50 km/h, will he get a photo radar ticket? 3. An object is moving at 4.66 m/s when it accelerates at 5.66 m/s 2 for a period of 2.35 s. The distance it moves in this time is m. Use the following information to answer the next question. 4. The automatic braking system in each car was designed to activate if the car encountered a sudden head-on force equal to or greater than 1.25 x 10 4 N. The activator uses an instrument that measures average force. In which cars would the braking system activate if each vehicle were forced to stop from 100 km/h in 4.0 s? a. 1, 2, and 4 b. 1,3, and 4 c. 2, 3, and 5 d. 2, 4, and 5 5. A bullet is fired straight up at 300 m/s. How high is it 1.34 s after firing?

2 6. A NASA space probe is moving towards Jupiter at a speed of 9.50 x 10 4 m/s. How far does it travel in 24.0 hours? 7. If the only forces acting on the object shown below are equal in magnitude, which one of the following statements is not possible? A. The object is at rest. B. The object is accelerating to the left. C. The object is moving with constant velocity to the right. D. The object is moving with constant velocity towards the top of the page. 8. A 10 kg box is dragged across a horizontal surface by a 50 N force. If the box is accelerating at 1.2 m/s 2, determine the magnitude of the force of friction. 9. An astronaut uses a force of 175 newtons to lift an 27.5 kilogram boulder at constant velocity to a height of meter above the planet s surface. What is the magnitude of the gravitational acceleration on the surface of the planet? 10. A child riding a bicycle at 2.40 m/s accelerates to 11.0 m/s in 14.0 seconds. What is the child s displacement at the end of this 4.0 s interval?

3 Use the following information to answer the next two questions. Two blocks are initially held together on a frictionless surface as shown in the diagram below. When the string is cut, the spring pushes the blocks apart. The 0.80 kg block accelerates at 0.32 m/s Determine the magnitude of the acceleration of the 0.40 kg block. 12. Once the spring stops pushing the blocks, the 0.80 kg block is moving at 0.54 m/s. Determine the speed of the 0.40 kg block. 13. On a snow-covered road, a car with a mass of kg collides head-on with a van having a mass of kilograms traveling at 8.0 m/s in the opposite direction. As a result of the collision, the vehicles lock together and then immediately come to rest. Calculate the speed of the car immediately before the collision. 14. A 1.2 kg ball moving due east at 40 m/s strikes a stationary 6.0 kg object. The 1.2 kg ball rebounds to the west at 25 m s. What is the veolcity of the 6.0 kg object after the collision?

4 15. A horizontal force of 207 N acts on a 7.80 kg bowling ball for s. The change in the ball s speed is m/s. 16. A space vehicle made up of two parts is travelling at 230 m/s as shown. An explosion causes the 450 kg part to separate and travel with a final velocity of 280 m/s as shown. Determine the resulting velocity (magnitude and direction) of the kg section. 17. A 150 kg cart moving at 13.0 m/s east collided with a 420 kg wagon moving at 5.00 m/s east. The cart rebounded westward with a speed of 3.00 m/s. What was the speed and direction of the wagon after the collision? 18. As a child catches a ball, he exerts a force, F, on the moving ball for a time interval, Δt. The mass of the ball is 250 g and its velocity changes from m/s to m/s as a result of the force. The magnitude of the impulse that the child applies to the ball is A kg m/s B kg m/s C kg m/s D kg m/s

5 19. Two carts, travelling at the same initial speed, move toward each other on a table, as shown below. Cart I has a total mass of 500 g and Cart II has a total mass of 250 g. When they collide, the carts remain together. Cart I will have i force acting on it than on cart II. After the collision, the two carts will move to the ii, because the momentum of Cart I is iii than the momentum of cart II. The above statement is best completed by the information in row Row i ii iii A a larger right larger B a larger left smaller C an equal right larger D an equal left smaller 20. Which of the following statements describes the situation shown above? A. Object B has a lower velocity. B. Object B has a higher velocity. C. Both objects travelled the same distance. D. Both objects started at the same location. 21. A ball is thrown straight up into the air, leaving the student s hand at 20 m/s. How long does it take for the ball to come to rest at its highest point before it begins to fall back to Earth?

6 The velocity of a car is graphed below. 22. When is the net force acting on the car equal to zero? 23. When is the momentum of the car the greatest? 24. When is the acceleration of the car the greatest? Use the following information to answer the next question. 25. What is the acceleration of the object in the interval 3.00 s to 7.00 s?

7 Answers m/s 2. No, speed is less than 50 km/h m/s 4. D m x 10 9 m 7. B N m/s m m/s m/s m/s m/s east m/s m/s right m/s east 18. A 19. C 20. B s 22. Between 4.0 and 6.0 s 23. Between 4.0 and 6.0 s to 4.0 s m/s 2