Physics Final exam Semester 2

What are energy stores?

Potential energy. It can be transformed into something useful.

Energy stores can be classified as…

Types of potential energy

Kinetic energy is the energy of…

Motion

Gravitational potential energy is:

GPE. energy due to position above ground

What is chemical energy?

Energy in a chemical bond, breaking chemical bonds require energy

What is elastic energy?

Energy in a stretched spring/elastic

What are types of energy transfers?

Electrical, thermal, radiation, mechanical(force)

What is the principle of conservation of energy?

Energy cannot be created or destroyed; it can only be stored or transferred .

Total energy in=

Total energy out

In which ways is energy, transferred as heat

Due to fictional forces and due to combustion

How do you calculate the energy efficiency?

Useful energy output/total energy input

What is nuclear energy?

Energy stored in the nucleus of atoms

What is the name of energy stored in hot objects?

Internal energy

What is the internal energy of an object?

The total kinetic energy and potential energy of the particles that make up that object. The faster, the particles move the more kinetic energy they have and the further apart they are the bigger potential energy there is.

What are three ways energy is lost

heat, friction and sound

what is the thermal energy?

Energy transferred from a harder place to a colder place because of the temperature difference.

What are the energy stores?

Kinetic energy, gravitational, potential energy, chemical energy, elastic energy, nuclear energy, internal energy, electrostatic energy

What is electrostatic energy?

Energy due to electric charge

What are four ways that energy can be transferred

• by force (mechanical working/ sound)

• By heating (thermal working)

• By radiation (light)

• By electrical currents (electrical working)

What is energy efficiency?

The fraction or percentage of energy supplied that is being usefully transferred

How to calculate the gravitational potential energy

Ep= mgh

How to calculate the kinetic energy

1/2 x mass x speed squared

What are non-renewable energy resource

An energy resource that is gone forever once it has been used

What are renewable energy resources?

An energy resource that will be replenished naturally when used

What are three energy resources that rely on the sun?

• Solar energy

• Wind energy

• Hydroelectric energy

What are two kinds of non-renewable energy resources?

Nuclear fuels and fossil fuels

Name two kinds of energy transfers going on in hydroelectric power stations

GPE→KE→Mechanical energy

Every energy resource has an effect on what?

The environment and natural habitats

What is work?

The amount of energy transferred when a force is applied.

Work, regarding force: The greater the force…

The more work it does

Work regarding distance in the direction of the force:

The further the object moves in the direction of the force, the more work it does

Energy transferred=

Amount of work done

What are two factors that work depends on

The size of the Force and distance moved by the force

What is the equation for work done?

W=F(N) x d(m)

What is power?

The rate at which work is done or the rate at which energy is transferred

How can you increase power?

• Lifting a heavier object in the same time

• Lifting the object more quickly

What is the equation for power?

P=W/t

What unit is used to measure power?

Watt (W)

How do you calculate weight?

W(Newtons) =mass(g) x 9.8

Describe the three states of matter

Solids: half particles that are close to one another and vibrate in place they have a fixed volume and shape

Liquids: Particles that are still close together, but space enough to slide past one another. They have a fixed volume and takes the shape of the container.

Gases: particles only interact with one another when they collide. There’s a lot of space between them. Takes volume of container and take shape of container.

What is the process of going from a solid to a gas called?

Sublimation

What is the process of going from a guest to a solid called?

Decomposition

What is temperature?

The average kinetic energy of the particles in a substance

What is needed to change states of matter

The particles need enough thermal energy added to overcome the attractive forces between the particles and separate them in order to increase their potential energy

What is the kinetic energy theory?

Describes matter as composed of small particles that are in random constant motion

What is absolute zero?

When the object becomes cold to the point that the particles lose all their kinetic energy

When temperature is increased, what happens to the potential energy of particles?

The potential energy increases since the particles are separated from one another

What is brown in motion?

The motion of small particles suspended in a liquid or gas cost by molecular bombardment. This happens because the moving particles collide with fast moving particles in the air.

What is evidence for the kinetic particle molecular theory?

For example:

Diffusion of perfume from one side of a room to another

Dissolved solid, mixing themselves in a liquid

Expansion of liquids as they boil

Expansion of most solids as they melt except ice

According to gas laws, what is the relationship between temperature pressure and volume?

T, P, and V are interrelated. When volume is constant pressure increases as temperature increases. When pressure is constant volume increases as temperature increases.

What unit is used to measure pressure?

Pascals (Pa)

What are the forms of the gas laws?

P1 V1=P2 V2.

P1/T1=P2/T2.

P1 V1/ T1 =P2 V2/T2.

The temperature has to be measured Kelvin (K)

Wave wave transfers___ but not____

Energy, matter

What is Wavelength?

The distance from one of the crest to the next or between two points on the wave which are in step. Measured in meters.

What is amplitude?

The distance from the surface of the water to the crest or trough

What is frequency?

The number of waves sent out each second measured in hertz

What is a period

T. The time taken for one complete wave to pass a point measured in seconds.

What happens when frequency is how constant and there is an increase in energy

The amplitude increases

if amplitude is held constant and there’s an increase in energy

The frequency increases

What is the relationship between wavelength and frequency?

They are inversely related. Therefore, as frequency increases, the wavelength gets shorter.

Regarding energy, what happens when the amplitude is bigger?

The more energy the wave transfers

What are transverse waves?

The particles carrying the wave move side to side, at right angles to the direction of the propagation of the wave.

What are longitudinal waves?

The particles carrying the wave move back-and-forth, along the direction of the propagation of the wave.

What happens when a wave travels from one material to another?

The wave speed changes.

What is a wavefront?

Align joining adjacent points on a wave that are all in step of one another

What is a ray?

A line perpendicular to the wavefront that show the direction of the wave travel

Reflection of waves:

The reflected wave will have a ray at the same angle to the normal as the incident race

Refraction of waves:

Is the bonding of a wave due to change in speed. A decrease in speed makes the reflected angle less than the incident angle and an increase in speed could be a change in density of the medium or in depth of the medium

What is diffraction of a wave?

It curse when a wave passes through a gap or around an obstacle.

When a fraction happens through a gap. The effect is greatest when the gap width is the same as the Wavelength. If the gap width is greater than the wavelength, the diffraction will only happen on edges.

Regarding wavelength on diffraction of waves:

The greater the wavelength of the wave, the greater the angle at which the wave is defected

main features of the electromagnetic spectrum

• The violent (ultraviolet) end of the spectrum is respected the the most and infrared is the least reflective

• Red light has a lower frequency than violet light

• It is made of transverse waves and they have different frequencies

• These waves travel at the same speed in a vacuum

• Red light has a bigger wavelength than violet light

What is the electromagnetic spectrum

The family of radiation similar to light

What is the order in which the waves in the electromagnetic spectrum are arranged?

( largest wavelengths, lowest frequency) Radio, waves microwaves, infrared radiation, visible light, UV light, x-ray, gamma rays. (smallest wavelength, highest frequency/most harmful.)

Hazards of the electromagnetic spectrum are:

UV and infrared can cause damage to skin and eyes through burns

X-rays and gamma rays can lead mutations if there’s too much exposure to them

Communicating using electromagnetic waves: what are satellites used for

They are used for transmission of information carried by electromagnetic waves