# Physics Chapter 7 Energy

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power

the bottom

### What task requires the most work: lifting a 50 kg sack 2 meters or lifting a 25 kg sack 4 meters?

both require the same amount of work

40 J

10 N

80 J

2 m

50 W

### Two identical arrows, one with twice the kinetic energy of the other, and are fired into a hay bale. The faster arrow will penetrate

twice as far as the slower arrow

16 times the KE

### A ball is projected into the air with 100 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is

100 J or less than 100 J

### Strictly speaking, more fuel is consumed by your car if an air conditioner, headlights, or even a radio is turned on. This statement is

almost always true

none

the 60 km/h car

potential energy

accelerations

### Compared to recoiling rifle, the bullet fired has

a great kinetic energy

### If a ping pong ball and a golf ball are both moving in the same direction with the same amount of kinetic energy, the speed of the ping pong ball must be

the same as the golf call

true

water

### If a beam of light were to go from either into water, which of the following would be true?

the light beam would bend away from the normal

### When light passes from a medium with a high index of refraction to a medium with a low index of refraction it will bend

away from the normal

### When light passes from a more optically dense medium into a less optically dense medium it will bend

away from the normal

true

true

false

true

false

wave

vibration object

### Like a transverse wave, a longitudinal wave has

amplitude, frequency, wavelength, and speed

### In a longitudinal wave, the compression and rarefactions travel in

the same direction

### The vibrations of a transverse wave move in a direction

at right angles to the directions of wave travel

### The vibrations of a longitudinal wave move in a direction

along the direction of wave travel

0.1 second

### A 60-vibration-per-second wave travels 30 meters in 1 second. Its frequency is

60 Hz and it travels at 30 m/s

0.5 Hz

none of these

waves test #17

2 m

halves

shortens

one wavelength

2 m/s

3 m/s

frequency

Example: