Energy

Question 1

What are the 8 main stores of energy?

Answer 1

1) chemical - eg. food and batteries
2) kinetic - eg. in a moving object
3) gravitational - eg. an object that is lifted above the planet
4) elastic - eg. in a stretched, squashed or twisted object
5) thermal- eg. in any object with a high temperature
6) magnetic- e.g in magnetic foreces between magnetic poles
7) electrostatic - eg. in electrical forces between charges
8) nuclear - e.g. in the immensely strong forces in atomic nuclei

Question 2

What are the 4 energy pathways?

Answer 2

1) mechanically - when a force acts and something moves
2) electrically - when a current flows
3) heating - temperature difference
4) radiation - waves such as light, microwaves and sound

Question 3

What is a system?

Answer 3

an object or group of objects

Question 4

What is a closed system?

Answer 4

• no energy can be transferred into or out of the system
• total energy remains constant

Question 5

What is an open system?

Answer 5

• energy can be transferred to or from it from outside of the system
• eg. from the surroundings

Question 6

What is the law of conservation of energy?

Answer 6

• energy cannot be created or destroyed, only dissipated, stored or transferred

Question 7

How can unwanted energy transfers be reduced?

Answer 7

• lubricating moving parts of machine to reduce friction
• improving thermal insulation to reduce energy tranferred to surroundings
• adding aluminium foil to the back of the radiator to reduce energy transferred by radiation

Question 8

How do we prevent heat loss from buildings?

Answer 8

• using loft insulation/ cavity wall insulation
• thermal conductivity of air is bad
• less heat energy could be tranferred into surroundings
• prevents convection

Question 9

What is thermal conductivity?

Answer 9

• the rate of energy transfer by conduction across the material

Question 10

What are materials with low thermal conductivity called?

Answer 10

insulators

Question 11

How do you investigate the effectiveness of different materials as thermal insulators?

Answer 11

1) put hot water from kettle into 100ml beaker
2) place the small 100ml beaker into large beaker with insulating material
3) put cardboard lid on large beaker with a hole for thermometer
4) place thermometer through lid and into water
5) record temperature of water and start stopwatch
6) record temperature of water every 3 minutes for 15 minutes
7) repeat steps 1-6, filling space in between the beakers with insulating materials
8) draw cooling curves for each insulator