Comp.Science midterm review and explain answers
A mass, on the end of a spring box, bobs up and down 1 complete cycle every 2 seconds. Its frequency is
0.5 Hz
A source of frequency of 500 Hz emits waves of wavelength 0.4 m, how long does the wave take to travel 600 m
3 s
The base velocity for the speed of sound at sea level is about how fast
740 Mph
At normal room temperature, sound travels a rate of about
741 m/h
One horsepower is equal to
746 watts
Sound is
A wave which travels through many materials but not a vacum
What type of machine is an axe and blade
A wedge
In the third class lever, the fulcrum is located
AT the opposite end of the resistane
The height of the wave above the baseline
Amplitude
If you push against a stationary wall, you do not work
At all
An object is raised above the ground gaining a certain amount of gravitational potential energy. If the same object is raised twice as high, it gains
Between four times as much potential energy and Twice as much potential energy the answer is neither
Which requires more work: lifting a 5-kg sack vertically 2 m or lifting a 25 kg sack vertically 4m
Both require the same amount of work
In a wind instrument like a clarinet the pitch is controlled by
Changing the length of the air column in the instrument
Which of the following is an example of potential energy
Coiled spring fully charged battery water behind a dam rock on top of a cliff
Which is a part of a longitudinal wave only
Compression
The two parts of a sound wave are
Compression and rarefaction
A system that detects the presents and the location of submerged objects objects y means of sonic and supersonic waves reflected back to it from the object
Sonar
Auditory impressions that transmit vibrations in the
Sound
Sound travels best through
Steel *or any solid object
The point on which a lever is supported and free to rotate is called
The fulcrum
The compression area of a sound wave is
The part of the wave where the molecules re the closest together
The law of machines states that in Ideal conditions
The work input must theoretically equal th work output
We set a speaker at the front of the room at ear level. The sound waves that pass thru' the room towards you will cause the air molecules in their path to?
They vibrate horizontally back and forward
A lever is composed of how many parts
Three
Which track has a higher pitched sound
Track 2 (bottom)
When an object is lifted 10m, it gains a certain amount of potential energy. If the same object is lifted 20m, its potential energy gain is
Twice as much
If you push an object just as far while applying twice the force ,you do
Twice as much work
If you push an object twice as far while applying the same force, you do
Twice as much work
a 1000 kg car and a 2000-kg car are hoisted the same distance in a gas station. Raising the more massive car requires
Twice as much work
If you do work on an object in half the time, your power output is
Twice the usual power output
Sound wave that has a frequency above 20,000 cycles per second
Ultra sonic waves
When mom complains that the amplitude to your music is to low she wants the volume to go
Up
In order for an object to produce sound it must
Vibrate
their is a loud speaker at the front of the room at ear level. The sound waves that pass thru' the room towards will cause the air molecules in their path to
Vibrate horizontally back and forward
The source of all sound w motion is a
Vibrating object
Who is the originator of the concept of horsepower
Watt
The distance from one wave crest to the next
Wavelength
Igor carried a skateboard up a hill and then rode the skateboard down the hill. When Igor reached the bottom of the hill, he rolled to a stop. When did Igor have the most potential energy
While standing on the skateboard at the top of the hill
F(D)= is the formula for
Work
The result of the exertion of a force through a distance is
Work
What determines power
Work and time
Sound travels best in
a solid
As an airplane approaches the speed of sound, powerful compression waves form
a sonic barrier
The repetition of a sound or signal caused by the reflection of a wave packet such a sound waves
sonar
A 50-kg sack is lifted 2 m in the same time as a 25 kg sack is lifted 4 m. The power expended in raising the 50 kg sack compared to the power used to lift the 25 g sack is
the same
Mach 1 refers to
the velocity in the air
First class lever
* Gain force increase speed change direction
First class levers may
*Gain fore Increase distance increase speed
Which of the following force is a resistance
*Gravity molecular Attraction friction
Used to measure the quality of sound
*frequency amplitude wavelength
What is a type of resistance
*gravity molecular Attraction friction
What class of lever is a wheelbarrow?
2nd
Exert 100 J in 50 sand your power output is
2w
A wave travels an average distance of 6 m in is. What is the waves velocity
6 m/s
The force that must be overcome in doing work
Resistance
Sound waves travels through what things
Solids, Liquids, Gases
It takes 40 J to push a box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box
10 N
How many vibrations per seconds are associated with a 101-MHz radio station
101,000,000
An ultrasonic waves is sent from a ship towards the bottom of the sea. It is found that the interval between the sending and receiving of the wave is 1.6 s. What is the depth of sea, if the velocity of sound in the seawater is 1400 m/s
1120 m
What kind of lever is a small teeter-totter
1st
Exert 1N for distance of 1M in 1s and you deliver a power of
1w
he maximum number of vibrations that can be heard by most people is
20,000 Hz
what is the lever in your arm
3rd
A TV set is pushed a distance of 2 m with a force of 20 n that is in the same direction as set moves. How much work is done on the set
40 J
A bow is drawn so that it has 40 J of potential energy . When fired, the arrow will ideally have a kinetic energy of
40 J
A man lifts a 15-pound box three feet, how much work is done
45 ft/lbs
using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 s. How much work is being done
50 W
One horsepower is equal to how much work per second
550 ft/lbs
The loudness of sound is measured in what units
Decibels
the power expended when a barbell is raised 2.0 m in 2 s is
Dependent on the mass of the barbell
the repetition caused by the reflection of sound waves
Echo
The law of conservation of energy states that
Energy may not be created or destroyed but it can be changed from
A watt is equal to the amount of work that is accomplished when a force of one newton moves an object a distance of one meter
False
The effort arm of a lever is the part of the lever that the applied force
False
You always get less out of a machine that you put in due to the force of gravity
False
When using a second class lever what will you gain
Force
The 'Pitch' of musical note is normally given in terms of its
Frequency
The number of vibrations an object completes in a sound
Frequency
As the temperature increases, the speed of sound
Increases
What happens to sound when the frequency of the sound wave increases
It becomes higher pitched
What is the best example of work being done on an object
Lifting a bag of groceries
An object that has potential energy must have this energy because of its
Location
What makes longer loud waves
Longer and taller waves
As the amplitude of a sound increases the
Loudness decreases
An object that has kinetic energy must be
Moving
The high or low quality of sound
Pitch
When a car is braked to a stop, it kinetic energy is transformed to
Potential energy
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
The speed of sound in the medium depends on upon
Properties of the medium
The unit of measurement for sound volume
decibel
Which of the following are not an important characteristic of sound
direction
What is not a type of wave
directional
Sound is classified as what
energy
a machine can save time or work
false
What must work contain
force and distance
through which material will sound travel the fastest
ice
A wave in which the molecules vibrate forward and backwards parallel to the direction that the energy is moving
longitudinal
Sound in air can best be described as a
longitudinal wave of air compressions and rarefactions
Amplitude controls which aspect of sound
loudness
who has longer vocal chords men-women
women have shorter vocal cords because they have higher voices