u, \""5 16. A ball suspended on a string can be used as an accelerometer. If such an accelerometer was constructed in a car, and a rider observed that the string made an angle of 15.0 backward with the vertical, what is the acceleration of the car? I E 15.0 : I a. 2.54 m/s2 b. 9.47 I'D/S2 c. 9.80 111st d. 0 m/s2 17. 18. 19. 20. To be considered in uniform circular motion a body must do what? a. move in a circular path b. maintain a constant speed c. maintain a constant distance from a centre point d. all of the above Which statement is true about an object in circular motion? a. It is not considered to be accelerating. b. It is accelerating only if its speed is changing. c. It is considered to be accelerating because its direction of motion is changing. d. It is considered to have a constant velocity. What is centripetal acceleration? a. the average acceleration of a body in uniform circular motion directed outward from the centre b. the instantaneous acceleration of a body in uniform circular motion directed outward from the centre c. the average acceleration of a body in uniform ciICular motion directed toward the centre d. the instantaneous acceleration of a body in uniform circular motion directed toward the centre A car is moving around a circular track. At the beginning of a time interval it is moving at 100 km/h north. At the end of the time interval it is moving at 100 km/h west. The average change in velocity of the car points approximately a. northwest b. northeast c. southwest d. southeast 21. 22. A ball is tied to the end of a string and whirled around a table in a horizontal circle. If the speed is doubled, how does the centripetal acceleration change? a. the centripetal acceleration is unchanged b. the centripetal acceleration is doubled c. the centripetal acceleration is tripled d. the centripetal acceleration is quadrupled A carousel has a radius of 12.0 m and turns once in 45.0 5. What is the speed of a rider on the edge of the carousel? a. 1.67 m/s b. 0.837 m/s c. 0.533 m/s (1. 0.267 mfs 23. 24. 25. 26. 27. 28. A rotating ride at an amusement park has a period of T. As the ride slows, at one point in time its period becomes 2T. How does the centripetal acceleration of rider change? a. b. c. (1. decreases by a factor of 2 decreases by a factor of 4 increases by a factor of 2 increases by a factor of 4 A centrifuge makes 2000 turns every minute. What is its frequency in hertz? a. b. c. d. A sample is placed in a centrifuge and rotated at a frequency f. If the frequency is doubled, how does the 2000 Hz 33.33 Hz 0.03 Hz 0.0005 Hz centripetal acceleration change? a. b. c. d. increases by a factor of 4 increases by a factor of 2 decreases by a factor of 4 decreases by a factor of 2 Which formula for centripetal acceleration is correct? a. b. c. d. lavc - 41?\": a: - 4117*:2 ac - 41.53:: at - 4x21"?! A curve on a highway is banked. Which statement is true? FL.\" 55"!\" The angle of bank is the same for all speeds of vehicles. Without the bank cars would not be able to drive around the curve. The bank assists the force of friction to help vehicles move in a circle. The road is banked outward on the curve. m1): What is the equation Fe - 7 derived from? a. b. c. d. Newton's First Law of Motion Newton's Second Law of Motion Newton's Third Law of Motion the Law of Inertia 29. An astronaut swings a ball on a string in a vertical circle in a clockwise direction, as shown. When the ball is at the top of the loop, the string breaks. Which way will the ball continue to move? a. up b. right c. down d. left 30. An object is on a rotating table, rotating with the table, as shown. A FBD drawn by a student is shown. What needs to be done to correct the FBD? The FBD is correct. The centripetal force pointing to the centre of the circle must be added. The centripetal force pointing outward from the circle must be added. The force of static friction should be the force of kinetic friction. P'PP