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

What happens when you rub your hands together?

Answer 12

Muscles do work to overcome the friction. Work is transferred as thermal energy to hands.

Question 13

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

Answer 13

How far it is raised
The weight

Question 14

Kinetic energy definition

Answer 14

Energy an object has due to it’s motion

Question 15

Elastic energy definition

Answer 15

Energy stored in an elastic object when stretched

Question 16

Spring constant

Answer 16

A measure of the stiffness of a spring

Question 17

Useful energy

Answer 17

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

Question 18

Wasted energy

Answer 18

Energy that isn’t usefully transferred

Question 19

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

Answer 19

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

Question 20

Dissipation effect on energy

Answer 20

As energy spreads out it becomes less useful

Question 21

Efficiency
Definition
How can it be written?
Key point?

Answer 21

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

Question 22

Input energy

Answer 22

Energy supplied to a device

Question 23

4 key ways to improve efficiency

Answer 23

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

Question 24

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

Answer 24

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 25

Power

Answer 25

Rate of energy transfer or energy per second

Question 26

How does the power an appliance has affect its energy?

Answer 26

More powerful appliance, faster rate it transfers energy