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