physics - energy/efficiency

Question 1

What is energy?

Answer 1

Energy is the ability to do work or produce change.

Question 2

True or False: Energy can be created or destroyed.

Answer 2

False: Energy cannot be created or destroyed, only transformed.

Question 3

Fill in the blank: The unit of energy is the ____.

Answer 3

Joule.

Question 4

What is an energy flow diagram?

Answer 4

An energy flow diagram is a visual representation of how energy moves through a system.

Question 5

Multiple Choice: Which of the following is NOT a form of energy? A) Kinetic B) Thermal C) Potential D) Mass

Answer 5

D) Mass.

Question 6

True or False: Potential energy is energy stored due to an object’s position.

Answer 6

True.

Question 7

Fill in the blank: The total energy in a closed system is ____.

Answer 7

Constant.

Question 8

What is the principle of conservation of energy?

Answer 8

The principle states that energy cannot be created or destroyed, only converted from one form to another.

Question 9

Multiple Choice: Which type of energy is associated with the motion of an object? A) Potential B) Kinetic C) Thermal D) Chemical

Answer 9

B) Kinetic.

Question 10

What does an energy flow diagram typically include?

Answer 10

It includes energy sources, pathways, transformations, and outputs.

Question 11

Fill in the blank: The energy conversion efficiency is calculated as the ratio of useful energy output to ____ energy input.

Answer 11

Total.

Question 12

Multiple Choice: Which of the following best describes thermal energy? A) Energy of motion B) Energy of position C) Energy due to temperature D) Energy in chemical bonds

Answer 12

C) Energy due to temperature.

Question 13

True or False: Energy can exist in multiple forms simultaneously.

Answer 13

True.

Question 14

Multiple Choice: Which energy transformation occurs in a hydroelectric power plant? A) Chemical to kinetic B) Kinetic to electrical C) Thermal to kinetic D) Potential to chemical

Answer 14

B) Kinetic to electrical.

Question 15

What role does energy play in ecosystems?

Answer 15

Energy flows through ecosystems, driving processes such as growth, reproduction, and nutrient cycling.

Question 16

True or False: All forms of energy can be converted into one another.

Answer 16

True.

Question 17

Fill in the blank: In an energy flow diagram, arrows represent the direction of ____.

Answer 17

Energy transfer.

Question 18

Multiple Choice: Which type of energy is stored in food? A) Kinetic B) Thermal C) Chemical D) Mechanical

Answer 18

C) Chemical.

Question 19

What are the 10 types of energy?

Answer 19

Magnetic, Kinetic, Heat (thermal), Light, Gravitational, Chemical, Sound, Electrical, Elastic, Nuclear.

Question 20

Which energies are included in a candle?

Answer 20

Heat+ Chemical+ Light.

Question 21

Which energies are included in a tennis ball?

Answer 21

Gravitational+ Sound+ Kinetic.

Question 22

Re-arrange this formula: F = ma

Answer 22

a = F/m

Question 23

Re-arrange this formula: p = mv

Answer 23

m = p/v

Question 24

How can you calculate efficiency using the formula?

Answer 24

Efficiency = Useful Output * 100% divided by Total Input.

Question 25

Useful Energy = wanted. Useless Energy = unwanted. True or false?

Answer 25

True.

Question 26

If you input is 100J and your wasted energy is 80J, how much is there of useful energy?

Answer 26

20J.

Question 27

Calculate the efficiency: A petrol engine that transforms 1000J of chemical potential energy into 300J of kinetic energy, and 700J into wasted heat and sound energy.

Answer 27

300J * 100% divided by 1000J will result in 30%, the efficiency of the question.

Question 28

What would the total input energy have to be for the following: A light bulb that is 50% efficient and transfers 40J of light.

Answer 28

40J * 50% (basically times by two or double) will give the result of 80J.

Question 29

Calculate how much energy is being transferred as useful energy: A 98% efficient kettle that has a total input energy of 2000J.

Answer 29

98% of 2000J is 1960J, the useful energy.

Question 30

Could you ever have a device that provides an efficiency of over 100%?

Answer 30

No, the total efficiency is 100%.

Question 31

In what form will a roller-coaster store energy at the top?

Answer 31

Potential energy. ## Footnote Example: A roller-coaster at the highest point has potential energy due to its height.

Question 32

A natural gas cooker transfers 200kJ of chemical energy to boil the water in a pan. When the water is boiling there is 168kJ of thermal energy stored in the hot water. How much wasted energy has been transferred and where did it go?

Answer 32

The amount of wasted energy is 32kJ and it was lost in the evaporation (smoke).

Question 33

Which three things should you look out for in Sankey Diagrams?

Answer 33

Labels, Arrows, Conservation.

Question 34

Where can you find CHEMICAL, THERMAL, KINETIC, GRAVITATIONAL and MAGNETIC.

Answer 34

Chemical = food, fuel, batteries Thermal = hot objects e.g a lamp Kinetic = moving objects Gravitational = masses lifted off ground Magnetic = magnets attract + repel

Question 35

Where can you find ELASTIC, NUCLEAR, ELECTRICAL, SOUND and LIGHT energy.

Answer 35

Elastic = stretched and compressed springs Nuclear = nucleus of an atom Electrical = electric charges attract + repel Sound = vibration in states of matter Light = emitted from luminous objects