1. When a star that is much larger than the Sun nears the end of its lifetime, it begins to collapse but continues to rotate. Which of the following describes the condi- tions of the collapsing star's moment of inertia (I), angular momentum (L), and angular velocity (w)? A. I increases, L stays constant, (.0 decreases. B. I decreases, L stays constant, 0.: increases. c. I increases, L increases, to increases. D. 7 I increases, L increases, to stays constant. -. . A40.0kg ice-skater glides with a speed of 2.0 m/s toward a 10.0-kg sled at rest on the ice. The ice-skater reaches the sled and holds on to it. The iceskater and the sled then continue sliding in the same direction in which the ice-skater was originally skating. What is the speed of the ice-skater and the sled after they collide? A. 0.4 m/s B. 0.8 m/s c. 1.6 m/s D. 3.2m/s A bicyclist applies the brakes and slows the motion of the wheels. The angular mome then decreases from 7 .0 kg-mz/s to 3.5 kg~m2/s over a period of 5.0 3. What is the angular impulse on each wheel? {.1 A. 0.7 kg-mz/s : B- -1.4 kg-mZ/s \"0. 2.1 kg-mz/s IV D- 3.5 kg-mZ/s ands at rest on the ice. A friend ' 45.0-k iceskater st g all. The skater and the ball trusses the skater a 5.0kg b ' . C3 en move backward across the ice With a speed of \"50 m/s. What was the speed of the ball at the .n oment just before the skater caught it? \" 2 5 m/s 0. 4.0 m/s 3.0 m/s D. 5.0 m/s the difference in momentum between a *' runner moving at a speed of 3.00 m/s and 0? kg ck moving at a speed of only 2850 kg-m/s 1. A force of 1 6. When the large gear in the diagram below rotates, it turns the small gear in the opposite direction at the same linear speed. The larger gear has twice the radius and four times the mass of the smaller gear. What is the angular momentum of the larger gear as a func- tion of the angular momentum of the smaller gear? Hint: The moment of inertia for a dish is 6) mrz, where m is mass and r is the radius of the disk. A' _2Lsmall c' \"8Lsmall B. \"4Lsmall D- "16Lsmall 6 N exerted against a rock with an impulse of 0.8 kg-m/s causes the rock to y off the ground with a speed of 4.0 m/s. What is the mass of the rock? 6. 1.6 kg n. 4.0kg A. 0.2kg B. 0.8 kg 8. An 82-kg hockey goalie, standing at rest, catches a 0.105 -kg hockey puck that is moving at a speed of 46 m/s. With what speed does the goalie slide on the ice? A. 0.059 m/s B. 0.56 m/s 9. A 12.0kg rock falls from a cliff to the ground directly below. Assuming the rock does not bounce, what is the impulse on the rock if its velocity at the moment it strikes the ground is 20.0 m/s downward? c. 1.2 m/s D. 5.3 m/s Chapter 9 - Standardized Test Practice 261
