P1 Conservation and Dissipation of Energy

Question 1

Energy can be stored in a variety of different energy stores

How can it be transferred?

Answer 1

Energy can be transferred by heating, by waves, by an electrical current, or by a force when it moves an object

Question 2

What happens to an object that falls and gains speed (energy stores)?

Answer 2

When an object falls and gains speed it’s gravitational potential decreases and its kenetic energy store increases.

Question 3

What happens when an object hits a ground?

Answer 3

It’s kenetic energy store decreases and it’s transffered to sound waves and the thermal energy store in the sourrounding increases

Question 4

Conservation of energy (and what does it apply to)?

Answer 4

Energy cannot be created or destroyed, at applies to all energy changes.

Question 5

What’s a closed system

Answer 5

A system in which no energy tranfers out off or into the energy stores of the system.

Question 6

What can happen to the energy store in a closed system?

Answer 6

Energy can transfer between the energy stores in a system, but the total energy within the system is always the same.

Question 7

When is work done

Answer 7

Work is done on an object when a force makes the object move

Question 8

Equation for work done

Answer 8

Energy transferred= work done

W= F x s (F is the force and s the distance moved)

Question 9

Energy transfer: Work done to overcome friction

Answer 9

Thermal energy stores of the objects rubbing together and to the surrounding.

Question 10

How could you alternate gravitaional potential energy

Answer 10

When an object moves up (increases) or moves down (decreases)

Question 11

Why does the gravitational potential store increase when an object is lifted

Answer 11

Because when lifted there is work being done on it to overcome the gravitational force (work done)

Question 12

How does the gravitational field strength differ from the Earth and the Moon

Answer 12

Earth’s is greater (stronger)

Question 13

Equation: change of gravitational potential energy

Answer 13

Change Gravitational potential energy store= mass x gravitational field strength x change of hieght

Change Ep= m x g x change h

Question 14

What does the kinetic energy of a moving object depend on

Answer 14

It’s speed and mass

Question 15

Equation: kenetic energy store

Answer 15

Ek = 1/2 m x v squared

Joules, Kg, m/s

Question 16

What is elastic potential energy

Answer 16

It’s energy in an elsatic object when work is done to it

Question 17

Equation: elastic potential energy (in a spring)

Answer 17

Ee= 1/2 k x e squared k= Spring constant e= extension

Joules, N/m, m

Question 18

What is useful energy

Answer 18

Energy in the place we want it and in the form we need it to be in.

Question 19

What’s wasted energy

Answer 19

Energy that is not useful energy and created by an undersired pathway

Question 20

What eventually happens to all wasted energy?

Answer 20

Transfers to the sourroundings, which become warmer

Question 21

What happens to energy as it dissipates (spreads out)?

Answer 21

Gets less and less useful

Question 22

Equation on the effciency of a device?

Answer 22

Useful energy transferred by the device/ total energy supplied to the device (x 100)

Question 23

What is the max energy transfer

Answer 23

No more than 100% efficient

Question 24

How do machines waste energy

Answer 24

Through friction by the moving parts, air resistance, electrical resistance and noise

Question 25

Can machines be more effective

How

Answer 25

Yes they can become more efficient, an example would be by lubricating a machine to reduce friction between moving parts.

Question 26

What does most of the energy supply you use in your house come from?

Answer 26

Electricity, gas and oil supply

Question 27

What do electrical appliances do?

Answer 27

The transfer energy in the form of useful enrgy at the flick of a switch

Question 28

What are uses of everyday electrical appliances

Answer 28

They include heating, lighting, making objects move, producing sound and visual images.

Question 29

What are electrical appliances designed for?

Answer 29

The are designed for a particula purpose and should waste as little energy as possible

Question 30

Whats power

Answer 30

Power is the rate of transfer of energy

Question 31

Equation for power of an appliance

Answer 31

P= E/t

Question 32

Equation of the efficiency of an appliance

Answer 32

Useful power put/ total power in (x 100)

Question 33

Equation of power wasted by an appliance

Answer 33

Power wasted by an appliance= total power input - useful power output