Conservation of Energy

Question 1

Give three examples of energy stores

Answer 1

Kinetic, thermal, chemical, gravitational potential, elastic, magnetic, etc

Question 2

Define a closed system, and give an example

Answer 2

A closed system is one where energy can flow in and out, but there is no transfer of mass.
Example: a pan of water being heated that has a lid on it, so no steam can escape

Question 3

What are the 4 ways in which energy can be transferred?

Answer 3

Mechanically, electrically, thermally and through radiation

Question 4

How do you calculate efficiency (%)

Answer 4

Useful energy ➗ total energy ✖️100

Question 5

Name three renewable energy resources

Answer 5

Wind turbines, tidal power, bio-fuels and solar cells

Question 6

Name 2 non-renewable energy resources

Answer 6

Fossil fuels (eg. coal) and nuclear fuels (eg. uranium)

Question 7

What is the principle of the conservation of energy?

Answer 7

ENERGY CANNOT BE CREATED OR DESTROYED, so the total energy of a system at any time must be the same

Question 8

What does the rate at which thermal energy is transferred through walls of a house depend on?

Answer 8

The difference in temp between outside and inside
Thickness of walls
Material of walls

Question 9

What is gravitational potential energy and how do you calculate it?

Answer 9

It is the energy possessed by a body due to its height above the earth

Change in GPE=mass x change in gravitational field strength x change in vertical height

Question 10

How do you calculate kinetic energy?

Answer 10

O.5 x mass x (speed)^2