Energy Transfers and Resources

Question 1

What are the different stores of energy?

Answer 1

Chemical, kinetic, gravitational, elastic, thermal, magnetic, electrostatic, nuclear

These stores represent the different forms energy can be found in.

Question 2

How can energy be transferred mechanically?

Answer 2

When gravity accelerates an object, giving it kinetic energy

This illustrates the conversion of potential energy into kinetic energy.

Question 3

What is an example of energy transfer by heating?

Answer 3

When a fire is used to heat up an object

Heating is a common method of energy transfer in everyday life.

Question 4

What is energy transfer by radiation?

Answer 4

When vibrations cause waves to travel through the air as sound or an object emits electromagnetic radiation

This includes examples like sound waves and light.

Question 5

What is the principle of energy conservation?

Answer 5

The total energy before is equal to the total energy after

This principle is fundamental in physics and indicates energy cannot be created or destroyed.

Question 6

How is efficiency calculated?

Answer 6

efficiency = useful energy output / total energy input × 100%

Efficiency measures how well energy is converted into useful work.

Question 7

What do Sankey diagrams represent?

Answer 7

The transfer of input energy into useful energy and wasted energy

Sankey diagrams visually depict energy flows and efficiencies.

Question 8

What is conduction?

Answer 8

Thermal energy in solids and liquids can be transferred by the vibration of particles

Conduction occurs primarily in solids where particles are closely packed.

Question 9

What are thermal insulators?

Answer 9

Non-metals that are usually poor conductors

Insulators are used to reduce unwanted energy transfer.

Question 10

How do metals conduct heat?

Answer 10

Electrons can leave the atoms and move freely among positively charged ions

This free movement of electrons allows metals to efficiently transfer heat.

Question 11

What is convection?

Answer 11

Thermal energy in fluids can be transferred by the movement of molecules from high to low thermal energy

Convection is essential in processes like heating water and air.

Question 12

What happens when a fluid is heated?

Answer 12

It expands, becomes less dense, and rises

This process drives the convection currents in fluids.

Question 13

Fill in the blank: Thermal energy in fluids can be transferred by _______.

Answer 13

convection

Convection is distinct from conduction, which occurs in solids.

Question 14

True or False: All materials are good conductors of heat.

Answer 14

False

Non-metals are typically poor conductors and serve as insulators.

Question 15

What is an example of convection in everyday life?

Answer 15

Water boilers and hot air balloons

These examples illustrate how convection currents operate in liquids and gases.

Question 16

What is thermal energy transferred by that does not require a medium?

Answer 16

Infrared radiation

Infrared radiation is part of the electromagnetic spectrum.

Question 17

What type of bodies are the best absorbers and emitters of radiation?

Answer 17

Black bodies with a dull texture

These bodies are effective due to their surface properties.

Question 18

What type of bodies are the best reflectors of radiation?

Answer 18

White bodies with a shiny texture

Shiny surfaces can reduce unwanted energy transfer.

Question 19

How does temperature and surface area affect infrared radiation emission?

Answer 19

Higher temperature and greater surface area increase infrared radiation emitted

This relationship is crucial for understanding thermal dynamics.

Question 20

What is work done defined as?

Answer 20

Work done = force × distance

This equation represents the relationship between force and movement.

Question 21

What does the conservation of energy link together?

Answer 21

Gravitational potential energy, kinetic energy, and work

This concept is fundamental in physics.

Question 22

What happens to a ball’s gravitational potential energy when it is dropped?

Answer 22

It becomes kinetic energy as it accelerates downwards

Gravity does work on the ball during this process.

Question 23

What is the formula for kinetic energy?

Answer 23

Kinetic energy = 1/2 mass × speed²

This reflects how speed affects kinetic energy.

Question 24

What is the formula for gravitational potential energy?

Answer 24

Gravitational potential energy = mass × gravitational field strength × height

This formula shows how potential energy is influenced by height.

Question 25

What is power a measure of?

Answer 25

The rate at which energy is transferred or work is done

Understanding power is essential for evaluating energy systems.

Question 26

What does a lamp with greater power do compared to one with lesser power?

Answer 26

It transfers more energy from electrical energy to light and heat in a given time

This explains why higher wattage lamps are brighter.

Question 27

Fill in the blank: Power = _______.

Answer 27

Work done / time

This formula provides a clear definition of power.