physcience chapter 8 classwork

1) Which requires more work: lifting a 50-kg sack vertically 2 m or lifting a 25-kg sack vertically 4 m? A) both require the same amount of workB) lifting the 25-kg sackC) lifting the 50-kg sack

A

12) A machine can multiply forces or A) distances B) work. C) energy. D) All of the above

A

3) An object lifted 10 m gains a certain amount of potential energy. If it is lifted 20 m, its gain in potential energy isA) twice as much. B) the same. C) four times as much.D) less.

A

5) An object may have potential energy because of itsA) location. B) speed. C) momentum D)acceleration

A

6) It takes 40 J to push a large crate 4 m across a floor. The force exertedon the crate isA) 10 N. B) 1600 N. C) 40 N. D) 160 N.E) 4 N.

A

8) Which has greater kinetic energy, a car traveling at 30 km/h oranother car of half the mass traveling at 60 km/h?A) the 60-km/h car B) the 30-km/h car

A

9) A music console is pushed a distance of 2 m with a force of 20 N. Thework done on the console isA)40 J. B) 2 J. C) 20 J. D) 80 J.E) 10 J

A

10) Raising an auto on a service station rack requires work. Raising ittwice as high requiresA) the same work, but twice the powerB) twice the work.C) twice the power.D) All of the above

B

11) Raising an auto on a service station rack requires work. Raising a twice-as-heavy auto the same vertical distance requiresA) the same work, but twice the power.B) twice the work. C) twice the power.D) All of the above

B

4) An object that has kinetic energy must beA) at an elevated position. B) moving. C) falling. D) at rest

B

7) A shopping cart moves with a kinetic energy of 40 J. If it moves attwice the speed, its kinetic energy isA) 80 J. B) 160 J. C) 40 J. D) not enough information

B

2) If you push an object twice as far while applying the same force, you do A) four times as much work.B) the same amount of work.C) twice as much work.

C

13) A model airplane moves three times as fast as another identical model airplane. Compared with the kinetic energy of the slower airplane, the kinetic energy of the faster airplane isA) the same for level flight.B) twice as much.C) four times as much.D) more than four times as much.3

D