47 terms

# Physics Chapter 7 Energy

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A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of
power
A block of ice sliding down an incline has it maximum speed at
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
A TV set is pushed a distance of 2 m with a force of 20 N. How much work is done on the set?
40 J
It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the force acting on the box?
10 N
A 2 kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground?
80 J
A 2 kg mass has 40 J of potential energy with respect to the ground. Approximately how high above the ground is it?
2 m
Using 100 J of work, a toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed to do this job was
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
A car moves 4 times as fast as another identical car. Compared to the slower car the faster car has
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
A woman carries a heavy box across a room at a constant speed. How much work does she do on the box while walking?
none
Which has greater kinetic energy, a car traveling at 30 km/h or a car of half the mass traveling at 60 km/h?
the 60 km/h car
An at rest may also have
potential energy
A heavy and a light object released from the same height in a vacuum have equal
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
Refraction results from differences in light's speed in different mediums. This statement is
true
The index of refraction for water is 1.33 while the index of refraction for ether is 1.47. Light will travel faster in the
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
The amplitude of a wave depends on how much work we do to the medium
true
the speed of a wave depends on how often we disturb the medium
true
Unlike transverse waves longitudinal waves do not have amplitudes
false
the period of the wave is defined as the time it takes for one complete cycle of a wave to occur
true
the length of the line from a to b is the wavelength of the wave
false
A wiggle in time is a
wave
A common source of wave motion is a
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
Which of the following is not a transverse wave?
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
In the frequency of a certain wave is 10 Hz its period is
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
An object that completes 10 vibrations in 20 seconds has a frequency of
0.5 Hz
An object that completes 100 vibrations in 5 seconds has a period of
none of these
A weight suspended from a spring bobs up and down over a distance of 1 meter in two seconds. Its frequency is
waves test #17
The amplitude of a particular wave is 1 meter. The top-to-bottom distance of the disturbance is
2 m
If you double the frequency of a vibrating object, its period
halves
You dip your finger repeatedly into water and make waves. If you dip your finger more frequently, the wavelength of the waves
shortens
During a single period the distance traveled by a wave is
one wavelength
As a train of water waves goes by, a piece of cork floating on the water bobs up and down one complete cycle each second. The waves are 2 meters long. What is the speed of the wave?
2 m/s
A skipper on a boat notices wave crests passing the anchor chain every 5 seconds. The skipper estimates the distance between the crest is 15 m. What is the speed of the water waves?
3 m/s
You are generating waves in a ripple tank with a certain frequency and wavelength. If you wanted to change the wavelength of these water waves then you would have to change the
frequency