P7 - Energy

Question 1

10 types of energy?

Answer 1

• Light energy
• Sound energy
• Thermal energy : Any object - the hotter the more energy it has
• Chemical: anything that can release energy by chemical reaction
• Elastic potential energy: anything stretched
• Gravitational potential energy: anything in a gravitational field
• Kinetic energy: Anything moving
• Magnetic energy: when magnetic objects repel or attract
• Nuclear energy: atomic nuclei release energy from this stores in nuclear reaction
• Electrostatic: When charged objects repel or attract

Question 2

What is the law of conservation of energy?

Answer 2

Energy cannot be created or destroyed but can be transferred from store to store

Question 3

What are the 4 ways energy can be transferred between stores?

Answer 3

1) Mechanically: an object moving due to a force acting on it (Pushing, pulling, stretching, compressing )
2) Electrically: A charge moving through a potential difference (like a charge moving around a circuit)
3) By heating: energy transferred from a hotter object to a colder object
4) By radiation: energy transferred by radiation (eg energy from sun reaching earth by light waves)

Question 4

Equation for efficiency?

Answer 4

Efficiency = useful output energy transfer / total input energy transfer

Question 5

Thermal energy energy equations?

Answer 5

Energy transferred = Mass x latent heat

Energy transferred = Mass x specific heat capacity x change in temperature

Question 6

Gravitational potential energy equation?

Answer 6

GPE = Mass x gravity x height

Question 7

Kinetic energy equation?

Answer 7

KE = 1/2 x Mass x velocity^2

Question 8

Elastic potential energy equation?

Answer 8

EP = 1/2 x spring constant x extension^2

Question 9

Electrical energy equation?

Answer 9

Power = Voltage x current

Question 10

Rate of energy transfer equation?

Answer 10

Power = Energy / time

Question 11

Work done equation?

Answer 11

Work = Force x distance

Question 12

What are the 4 types of potential energy?

Answer 12

• Gravitational potential energy
• Elastic potential energy
• Chemical
• Nuclear

Question 13

What does the Specific heat capacity experiment look like?

Answer 13

A circuit with an ammeter and voltmeter (to measure the current and voltage of circuit) connected to a heater.
The heater is in a beaker with a thermometer filled with water. The beaker of water is covered with an insulator.

Question 14

What are the two ways to prevent energy loss?

Answer 14

1) Lubrication: Oil moving parts to prevent friction

2) Insulation: making sure not thermal energy is lost

Question 15

Air and insulation:

Answer 15

When air is trapped it is a good thermal insulator.

• This is why bubble wrap is a good insulator
• Double or triple glazed windows trap air as insulation in homes

Question 16

What is a control, independent and dependent variable?

Answer 16

Control variable: The aspects we keep the same in an experiment

Independent variable: The aspects change in an experiment

Dependent variable: The aspects that we measure in an experiment

Question 17

4 ways to reduce thermal conductivity (heat transfer) from homes?

Answer 17

1) Pack cavities between layers of bricks in walls with a thermal insulator
2) double glazed windows trap air particles (a good thermal conductivity)
3) Loft insulation reduce heat transfer out of roof
4) Build houses with thicker walls

Question 18

Installations to prevent heat transfer from homes?

Answer 18

• Fill cavities between layers of brick in walls with insulating materials
• Loft installation
• Double glazed walls
• carpet
• Thick curtains