P1 Energy and Dissipation

Question 1

What is the equation linking kinetic energy, mass and velocity?

Answer 1

Energy = 1/2 x mass x velocity^2

Question 2

How do you find graviational potential energy?

Answer 2

Gravitational potential energy = weight x change in height

Question 3

What is the scientific unit for graviational field strength?

Answer 3

Newtons per kilogram

Question 4

What is the equation linking power, time and energy?

Answer 4

Power = energy/time

Question 5

Which energy store changes as height of an object changes?

Answer 5

Graviational Potential Energy

Question 6

Which two energy stores changes depending on the position of the object?

Answer 6

Gravitational Potential Energy
&
Elastic Potential Energy

Question 7

For something that is falling, what is the relationship between Kinetic Energy and Gravitational Potential Energy?

Answer 7

Inverse proportion; as Kinetic energy increases, Gravitational energy decreases

Question 8

Which type of energy is stored in an inflated balloon?

Answer 8

Elastic Potential Energy

Question 9

What is the Law of Conservation of Energy?

Answer 9

Energy is stored and transferred.

• not created or destroyed

Question 10

What is energy?

Answer 10

Energy is the ability to do work.

Question 11

What are the energy stores?

Answer 11

1) Kinetic
2) Chemical
3) Gravitational
4) Elastic
5) Thermal
6) Magnetic
7) Nuclear

Question 12

What is kinetic energy?

Answer 12

Energy in a moving object

Question 13

What is chemical energy

Answer 13

Energy in a fuel or battery

Question 14

What is graviational energy?

Answer 14

Energy in an object above the ground

Question 15

What is elastic energy?

Answer 15

Energy in a streched or squashed object.

Question 16

What is thermal energy?

Answer 16

Energy due to a substance’s temperature.

Question 17

What is magentic energy?

Answer 17

Energy in 2 seperated magnets (attract/repel)

Question 18

What is nuclear energy?

Answer 18

Energy in radioactive decay.

Question 19

What are the energy transfers?

Answer 19

• Waves
• Heating
• ‘Electrical current’
• Mechanical

Question 20

What is a closed system?

Answer 20

A system in which no energy transfers take place out of or into the energy stores of the system.

Question 21

Energy transferred is equal to

Answer 21

Work done

Question 22

How do you calculate work done?

Answer 22

Work done = force x distance
(J) (N) (m)

Question 23

How to find change in graviational potential energy?

Answer 23

Change in graviational potential energy = weight x change in height

Question 24

How to calclate weight?

Answer 24

Weight = Mass x Gravaitional field Strength (9.8N/Kg)

Question 25

How to find elastic potential energy?

Answer 25

Elastic potential energy = 1/2 x spring constant x extention^2

Question 26

What is useful energy?

Answer 26

Energy in the place and form we want it in.

Question 27

What is wasted energy?

Answer 27

Energy that is not useful and is transferred by an undesired pathway.

Question 28

What happens to wasted energy?

Answer 28

It is eventually transferred into the surroundings, which become warmer.

Question 29

How to calculate efficiency?

Answer 29

Efficiency = useful output energy transfer / total input energy transfer
or
Efficiency = useful power output / total power input

Question 30

How do you calculate work done?

Answer 30

Work done = force x distance

Question 31

What does kinetic energy depend on?

Answer 31

Its mass and speed.

Question 32

How do machines waste energy?

Answer 32

• Friction between moving parts
• Air resistance
• Electrical resistance
• Noise

Question 33

Give an example on how we can reduce the amount of energy wasted in machines?

Answer 33

Lubrication to reduce friction between moving parts.

Question 34

What is power?

Answer 34

The rate of transfer of energy.

Question 35

What is power measured in?

Answer 35

Watts (W)