YEAR 9 Energy Stores, Resources, Transfers And Efficiency

Question 1

What is the equation for gravitational potential energy?

Answer 1

GPE= mxgxh (mass in kg x gravitational field strength x change in vertical height in m

Question 2

What is the equation for kinetic energy?

Answer 2

KE = 1/2 x m x v 2 (kinetic energy in J = 1/2 x mass in kg x speed m/s 2)

Question 3

What is the equation for efficiency?

Answer 3

Efficiency = useful energy transferred by device / total energy supplied to device

Question 4

Describe the conservation of energy

Answer 4

We can’t lose or gain energy: it can be transferred usefully, stored or dissipated, it cannot be created or destroyed.

Question 5

List the energy stores:

Answer 5

Kinetic
Nuclear
Magnetic
Chemical
Thermal (internal)
Gravitational potential
Elastic potential
Electrostatic

Question 6

List the energy transfers:

Answer 6

Heating
Radiation
Work done by a force
Work done by a current

Question 7

List 3 ways that you can reduce unwanted energy.

Answer 7

Thermal insulation
Lubrication
Streamlining

Question 8

What is thermal insulation?

Answer 8

A common way in which energy is wasted through thermal energy, but the insulation doesn’t allow this to happen by trapped the energy so that it can’t escape.

Question 9

What is lubrication?

Answer 9

Energy can be lost due to friction, and different lubricants can prevent this (e.g. oil).

Question 10

What is streamlining?

Answer 10

When objects travel through the air, they experience air resistance. In order to combat this, we can streamline objects, such as aeroplanes to reduce the amount of air resistance.

Question 11

Describe how we can increase efficiency in the home.

Answer 11

To reduce thermal energy being transferred to a warm house, the walls can be built thicker, so that the energy must travel further before it is transferred to the outside. Thermal energy transfers can be reduced further if there are two walls with an air gap between them, as air has a lower thermal conductivity compared to the brick.

Question 12

How can we increase efficiency?

Answer 12

Efficiency can be increases by improving technology and processes. This can include using energy efficient appliances and machinery, optimising production lines, implementing better insulation and adopting more efficient transportation systems.