Science short answer

You exert a force of 300n to lift a box 2m from the floor to a shelf in 3s. How much power did you use?

(300 x 3)/3 600/3= 200j/s

What is the formula for kinetic energy?

(mass x velocity^2)/2

At 0 degress C, sound travels through air at a speed of 330m/s. How long would it take sound to travel a distance of 1000m?

1000m/330m/s= 3.03s

If the speed of sound in air is 330m/s, calculate the wavelength of the highest frequency sound heard by humans. Use the following formula: wavelength=speed/frequency

330/20,000= .0165

A student stands at the edge of a diving board into hell that is 3m high. The student's weight is 350N. What is the student's gravitational potential energy?

350 x 3 = 1050J

How do scientists know that Earth's magnetic field has changed over time?

By studying the layers of rock and the iron that is locked into place over time.

An eagle flies from its perch in a tree to the ground to capture its prey. Describe its energy transformations as it descends.

Eagle starts with potential energy due to its high position. When it leaves the perch mechanical energy moves the eagle. This is also an increase in kinetic energy and decrease in potential energy as it descends.

Explain how Earth can act as a magnet marker. How can you speed up the process?

Earth's magnetic field may attract domains in an iron bar strongly enough to cause them to line up in the same direction. You can speed up this process by gently tapping on the bar with a hammer. This vibrates the domains and they will align easier.

How did Albert Einstein's theory of relativity change the law of conservation of energy?

He said that energy can sometimes be created by destroying matter

What might happen if you drop a permanent magnet or strike it hard?

It can lose it magnetism. They domains can be knocked out of alignment.

What is the unit of measure for specific heat?

Kelvin

An orange falls from its greatest height. What kind of energy increases and what kind of energy decreases?

Kinetic increase and potential decreases

Describe the differences between kinetic and potential energy.

Kinetic: energy do to change in motion. Potential: energy stored and held in readiness due to the objects position.

List 6 forms of energy and give an example of each

Mechanical: school bus moving Thermal: particles moving faster in ice cream as it melts Chemical: energy in food compounds Electrical: shock from metal door knob Electromagnetic: lights in house Nuclear: atomic bomb

Two cyclists are riding their bikes up a steep hill. Jessica rides her bike straight up the hill. Adrian rises his bike up the hill in a zigzag path. Adrian and Jessica have identical masses. Once they reach the top of the hill, does Adrian have less gravitational potential energy than Jessica? Explain your answer.

No because both bikers have the same mass and the height of the hill is the same.

What is the formula you use to calculate power?

Power=work/time or Power= (Force x Distance)/Time

Explain how destructive interference can be used in earphones to cancel out the noise of airplane engines.

The headphones produce such a wave that interferes destructively with the sound of the engine.

A motorcycle, an automobile, and bus are all traveling at the same speed. Which has the least kinetic energy? The greatest kinetic energy? Explain.

The motorcycle has the least kinetic energy because it has the least mass. The bus has the most kinetic energy because it has the most mass.

Wbat are the functions of the outer ear, middle ear, and inner ear?

The outer ear tunnels sound waves. The middle ear transmits the waves inward. The inner ear converts the sound waves into a form your brain can understand.

Which particles are moving faster, the particles of a mug of hot cocoa or the particles of a glass of cold chocolate milk?

The particles of a mug of hot cocoa since it has a higher temperature

Suppose a sound is made far away from you. When do you hear the sound?

The sound causes a disturbance that moves through the air. You hear the sound, once that disturbance reaches your ear

What happens if you break a magnet in two?

You end up with two magnets

A 500N girl walks down a flight a stairs so that she is 3m below starting level. What is the change in the girl's gravitational potential energy?

a decrease in 1500J. (500N x 3m)

As a car drives past you, the driver keeps a hand on the horn. Describe what you hear as the car approaches you then passes by.

as the car moves towards us, the waves reach us at a higher frequencey. This makes the pitch increase. As the car moves further away the wave reach at a lower frequencey and the pitch decreases.

Thunder and lightning happen at the same time. Why do you think you usually see lightning before you hear the thunder?

because light travels faster than sound. You see the light before the disturbance of the sound reaches your ears

What are two ways to make a magnet from an unmagnetized ferromagnetic material?

by placing it in a strong magnetic field or by rubbing it with one pole of a strong magnet

What is the formula you use to determine the gravitational potential energy of an object?

either mass x height or mass x gravitational acceleration x height

What does the law of conservation of energy state?

energy cannot be created or destroyed

How can loud noises damage your hearing?

loud sounds can damage the hair cells on the cochlea and this makes its less effective at detecting sounds signals

The poles of a magnetized needle on a compass align themselves with Earth's ___________________.

magnetic field

The kinetic energy of an object depends on both its _______ and _________

mass and velocity

Because velocity is squared in the kinetic energy equation, doubling an object's velocity will ___________ its kinetic energy.

quadruple

A compass points North until a bar magnet is brough next to it. The compass needle is then attracted or repelled by the magnet. What inference can you make about the strengths of the magnetic fields of Earth and the bar magnet?

the bar magnet has a stronger magnetic field than that of the Earth at that position.

Describe how domains in a magnetized differ from those in an unmagnetized material.

the domains in magnetized material point in the same direction. The domains in unmagnetized point in random directions.

Think of a metal spoon in a pot of hot water. How do the particles of the water affect the particles of the spoon?

the particles of the hot water are moving faster than the spoon and as the thermal energy of the water transfers to the spoon the spoon increases in temperature.

When the magnetic fields of two or more magnets overlap, what is the result?

they result in a combined field.

Describe the process of energy conversion from potential energy to kinetic energy as water falls from the top to the bottom of the Niagra Falls.

water at the top has highest potential energy. Potential decreases and kinetic increases as the water falls to the bottom.

Describe the conversion of chemical energy to mechanical energy in your body.

your body converts the chemical energy in the food you eat to the mechanical energy you need to move your muscles