Energy Stores

Question 1

What is energy?

Answer 1

The capacity to do work

Question 2

What are the types of energy stores?

Answer 2

Chemical, thermal, kinetic, grav. potential, elastic, magnetic, electrostatic, vibration, nuclear

Question 3

Chemical store example

Answer 3

Batteries, anything that we can eat or burn

Question 4

Thermal store example

Answer 4

Anything hot = cup of hot tea

Question 5

Kinetic store

Answer 5

Anything moving = e.g a moving car

Question 6

Gravitational potential store example

Answer 6

Anything that can fall down (and therefore have gravity act upon it) = a ball on top of a hill

Question 7

Elastic store example

Answer 7

Anything that can stretch or compress = e.g an elastic band

Question 8

Magnetic/electrostatic store example

Answer 8

Anything with an electrostatic or magnetic field = eg. Two north poles of magnets near each other

Question 9

Vibration store example

Answer 9

Anything that vibrates = e.g atoms in a solid

Question 10

Nuclear store

Answer 10

Any nuclei of any atom = e.g nuclear bomb

Question 11

Name the 4 ways that energy can be transferred

Answer 11

• mechanically
• electrically
• heating
• radiation

Question 12

Describe how energy is transferred mechanically

Answer 12

A force causes energy to be transferred

Question 13

Describe how energy is transferred electrically

Answer 13

An electric current causes energy to be transferred

Question 14

Describe how energy is transferred through heating

Answer 14

Energy transfer due to a temperature difference ( e.g convection or conduction)

Question 15

Law of conservation of energy

Answer 15

Energy cannot be created or destroyed (only transferred between stores).

Question 16

Describe how energy is transferred through radiation

Answer 16

Energy transferred as a wave such as light (EM) or sound

Question 17

How is the kinetic store increased?

Answer 17

• move faster
• larger mass that is moving

Question 18

How is the GP store increased?

Answer 18

• more mass
• higher from ground
• stronger grav. field strength

Question 19

What is efficiency?

Answer 19

The percentage of energy that is being transferred usefully out of the total input energy

Question 20

What is work done?

Answer 20

When an object is moved over a distance by a force applied in the direction of displacement

Question 21

What is work done measured in?

Answer 21

Joules (J)

Question 22

How do you draw a Sankey diagram?

Answer 22

1. Measure out a scale to represent the total input energy (e.g 8cm for 400J)
2. Draw out the percentage of usefully transferred energy out (e.g 3/4 of 8 is 6cm)
3. Draw out the percentage of wasted energy out
4. The combined length of both lines must be equal to the length of the line for total input energy

Question 23

How would you calculate kinetic energy or gravitational potential energy from work done?

Answer 23

Work done = energy transferred therefore these values should be equal

Question 24

What must happen for work ‘to be done’ by a force?

Answer 24

the object having work done to it must :
- move a distance
- the object must move in the same direction of the force applied

Question 25

When an object is falling (e.g a ball being dropped) what stores increase and decrease?

Answer 25

• the gravitational potential store of the ball is decreasing as it falls
• the kinetic store of the ball is increasing as it falls