1. A 10-kg mass is held 1.0 m above a table for 25 s. How much work is done during that period? (a) none (b) 10 J (c) 250 J (d) 9.8 J (e) none of these.
5. If a 20-kW engine can raise a load 50 m in 10 s, how long will it take for it to raise that same load 100 m? (a) 20 s (b) 40 s (c) 5.0 s (d) not enough information (e) none of these.
8. If this book is placed on an ordinary table and slid along a path that brings it back to where it started, (a) no net power will have been required (b) work will certainly have been done (c) assuming a conservative gravitational field, no net work will be done (d) not enough information is given to say anything about the work done (e) none of these.
10. Work is done on an object far out in space where it has negligible gravitational-PE. If in the process there is no net change in its KE, we can conclude (a) that friction may have been operative (b) that this situation is impossible (c) that the energy of the object has decreased (d) that the object’s speed decreased (e) none of these.
12. A kid in a wagon rolls from rest down a hill reaching the bottom at 12 m/s. On the next run, she gets a push and starts down at 5.0 m/s. At what speed does she now arrive at the bottom? (a) 12 m/s (b) 17 m/s (c) 7 m/s (d) 13 m/s (e) none of these.
14. How fast must a 1.0-kg mass be moving if its kinetic energy is 1.0 J? (a) 1.0 m/s (b) 9.8 m/s (c) 1.414 m/s (d) 10 m/s (e) 0.102 m/s.
16. How high above the Earth’s surface must a 1.0-kg mass be for it to have a gravitational-PE of 1.0 J with respect to that surface? (a) 9.8 m (b) 1.0 m (c) 0.10 m (d) 0.01 m (e) 32 m.
17. While a ball rolls down the circularly curved track shown in Fig. MC17, its speed, acceleration, and kinetic energy, respectively
 |
(a) increase, increase, increase (b) decrease, decrease, decrease (c) increase, decrease. decrease (d) decrease, increase, increase (e) none of these. |