P1- Conservation and dissipation of energy

Question 1

8 energy stores

Answer 1

Kinetic
Heat/thermal
Magnetic
Gravitational potential
Chemical
Elastic potential
Electrostatic
Nuclear

Question 2

4 ways of energy transfer

Answer 2

Mechanical
Electrical
Heating
Radiation

Question 3

How do Sankey diagrams work?

Answer 3

One arrow then splits into two or more points, showing transfer of energy to dif stores

Question 4

Closed system definition

Answer 4

No energy is dissipated into the surroundings

Question 5

Conservation of energy definition

Answer 5

Energy can be stored and transferred but never created or destroyed

Question 6

Pendulums
Movement and energy stores?
Constant speed?
In vacuum?

Answer 6

-Moves towards middle, gravity changes store from GPE to KE
-Moves away from middle, KE to GPE
-Air resistance slows it down, thermal energy to surroundings
-If in vacuum, no air resistance,swing forever

Question 7

Bungee jumping

Answer 7

High GPE to KE to EPE
Comes to stop with all energy as EPE
EPE to KE to GPE
Lower height as energy transferred to surroundings

Question 8

Work definition

Answer 8

Energy transfer when a force moves an object through a distance

Question 9

What does energy transferred equal?

Answer 9

Work done

Question 10

Amount of work done depends on 2 things?

Answer 10

Size of force acting
Distance the objects moves

Question 11

Work done to overcome friction is transferred to…?

Answer 11

Thermal energy store

Question 12

Energy needed for an object to be raised depends on 2 things?

Answer 12

How far it is raised
The weight

Question 13

Kinetic energy definition

Answer 13

Energy an object has due to it’s motion

Question 14

Elastic energy definition

Answer 14

Energy stored in stretched spring or rubber band

Question 15

Spring constant

Answer 15

A measure of the stiffness of a spring

Question 16

Useful energy

Answer 16

Energy transferred to where it’s wanted in the way it’s wanted

Question 17

Wasted energy

Answer 17

Energy that isn’t usefully transferred

Question 18

Friction
What happens when two surfaces rub together?
How to reduce friction?
Effect on surroundings?

Answer 18

Friction causes them to heat up
Lubricant, less heat wasted
Wasted energy transferred to surroundings, become warmer

Question 19

Dissipation effect on energy

Answer 19

As energy spreads out it becomes less useful

Question 20

Efficiency
Definition
How can it be written?
Key point?

Answer 20

Proportion of energy transferred usefully
Percentage or decimal number
Can’t be greater than 100%

Question 21

Input energy

Answer 21

Energy supplied to a device

Question 22

3 key ways to improve efficiency

Answer 22

Lubricate moving parts to reduce friction
Use low resistance wires
Cut out noise

Question 23

Useful and wasted energy for a light bulb, kettle and hairdryer

Answer 23

Light bulb U-light emitted W-heat emitted
Kettle U-energy heating water W-energy heating kettle
Hairdryer U-energy to blow air W-sound of motor

Question 24

Power

Answer 24

Rate of energy transfer or energy per second

Question 25

How does the power an appliance have affect the energy?

Answer 25

More powerful appliance, faster rate it transfers energy