2B3 Energy

Question 1

Define:

energy

Answer 1

The ability to do work.

Energy can be categorised into potential and kinetic energy.

Work involves moving an object by force.

Question 2

List four types of potential energy.

Answer 2

1. Chemical energy
2. Elastic energy
3. Gravitational energy
4. Nuclear energy

Potential energy is the energy stored in an object due to its position or arrangement.

Question 3

Name five types of kinetic energy.

Answer 3

1. Electrical Energy
2. Radiant Energy
3. Thermal Energy
4. Sound Energy
5. Mechanical Energy

Kinetic energy is energy in motion.

Question 4

List three examples of kinetic energy.

Answer 4

1. A ball rolling down a hill.
2. Dogs running.
3. Cars driving.

The kinetic energy of each of these examples can be calculated using the equation, KE = 1/2 mv².

Where m is the mass and v is the velocity.

The KE equation shows how velocity plays a greater role due to its squared value.

Question 5

List three examples of potential energy.

Answer 5

1. A ball at the top of a swing.
2. A car stopped at the top of a hill.
3. Books on a shelf.

The potential energy (PE) of each of these examples can be calculated using the equation, PE = mgh.

Where m is the mass, g is gravity, and h is the height.

PE equation demonstrates how position influences energy storage.

Question 6

Fill in the blank:

Kinetic energy can be transferred, while potential energy _______.

Answer 6

cannot

Kinetic energy is transferred when a moving object applies force to another object. Potential energy cannot be transferred because it is based on position. Once the position changes, the energy becomes kinetic.

Example: Bowling a ball transferring energy to pins.

Question 7

What happens to kinetic energy when a ball is thrown into the air?

Answer 7

It is converted into potential energy at the top of the arc.

Kinetic energy can be converted to potential energy when a moving object stops moving.

Potential energy can be converted into kinetic energy when a stationary object starts to move.

Question 8

What is a practical application of kinetic energy?

Answer 8

Wind turbines converting motion into electrical energy.

Demonstrates renewable energy use.

Question 9

Define:

chemical energy

Answer 9

Energy stored in the bonds of chemical compounds.

Stored energy is released during chemical reactions, such as combustion.

Question 10

How is chemical energy used in batteries?

Answer 10

Chemical reactions in the electrolyte create a flow of electrons, generating electricity.

This process involves an anode and cathode.

Question 11

Fill in the blanks:

Energy is _______ when bonds are broken but _______ when bonds are formed.

Answer 11

absorbed; released

Formation of bonds is an exothermic process while breaking of bonds is an endothermic process.

Question 12

What process do plants use to store chemical energy?

Answer 12

Photosynthesis

During photosynthesis, carbon dioxide and water are converted into glucose, storing energy.

Question 13

How do exothermic reactions produce heat?

Answer 13

More energy is released during bond formation than is absorbed during breaking bonds.

Examples include combustion and hand warmers.

In endothermic reactions, more energy is absorbed during breaking bonds.

Question 14

What are the contents of hand warmers that allows them to produce heat?

Answer 14

• Iron powder
• Water
• Salt
• Carbon

The reaction between iron and oxygen forms rust, releasing heat.

Question 15

What is an example of chemical energy in daily life?

Answer 15

Burning wood.

Releases stored energy as heat and light.

This is an exothermic process.

Question 16

What is the primary source of chemical energy in food?

Answer 16

Solar energy

Food energy is ultimately derived from the Sun through various food chains.

Question 17

What is the difference between electricity and electrical energy?

Answer 17

• Electricity: The flow of charges.
• Electrical energy: The work done by these charges.

Example: Static electricity is electrical energy, not electricity.

Electric energy is measured in Joules, and electricity is measured in Watts.

Question 18

What is the role of electrons in electrical energy?

Answer 18

Moving electrons create electrical energy.

Electric fields influence movement.

The faster the electrons move, the more electrical energy they create.

Question 19

Define:

static electricity

Answer 19

Electricity that gathers in one place due to the buildup of electric charges.

It often occurs when two objects are rubbed together.

Example: The charge buildup from rubbing a balloon on hair.

Static electricity is a form of potential energy since charges in static electricity are stationary until discharged.

Question 20

Define:

current electricity

Answer 20

Electricity that moves from one place to another.

This type of electricity powers homes and electrical devices.

It is a form of kinetic energy.

Question 21

What is electromagnetism?

Answer 21

The relationship between electricity and magnetism.

Electric current produces a magnetic field, and a changing magnetic field can produce an electric current.

Question 22

List some common units of electrical energy.

Answer 22

• Ampere (A)
• Coulomb (C)
• Joule (J)
• Watt (W)
• Volt (V)
• Kilowatt-hour (kWh)

These units measure various electrical properties such as current, charge, energy, power, and potential difference.

Question 23

List five examples of electrical energy.

Answer 23

1. Batteries that power electronic devices
2. Lightning
3. Electrical charges moving through a wire
4. Static electricity
5. Capacitors storing electric energy

These examples illustrate various forms of electrical energy in different contexts.

Question 24

Define:

nuclear energy

Answer 24

A form of energy released from the nucleus of atoms.

Defined as energy produced from nuclear processes, distinct from chemical energy.

Question 25

List *two* **types of nuclear reactions** that produce nuclear energy.

Answer 25

1. Fission 1. Fusion ## Footnote Fission splits a nucleus, and fusion combines nuclei.

Question 26

What occurs during **nuclear fusion**?

Answer 26

Two hydrogen nuclei combine to form a helium nucleus. ## Footnote This process releases a massive amount of energy due to mass defect. Mass defect occurs when the mass of the products is less than the mass of the reactants.

Question 27

What is the **primary element** involved in nuclear fission?

Answer 27

Uranium ## Footnote Uranium is a heavy metal with 92 protons and is commonly used in nuclear reactors.

Question 28

What is the **role of water** in a nuclear reactor?

Answer 28

* Absorbs heat from a nuclear reaction preventing it from going out of control. * Helps generate steam for electricity.

Question 29

What is a **nuclear power plant**?

Answer 29

A facility that **harnesses energy released** during a nuclear reaction to generate electricity. ## Footnote Operates primarily through controlled fission reactions. The world’s first nuclear power plant switched on in 1951. It powered four 200-watt light bulbs.

Question 30

List *three* **applications** of nuclear energy.

Answer 30

1. Powering cities. 1. Fueling submarines. 1. Fueling space probes. ## Footnote Nuclear energy is versatile but also produces radioactive waste.

Question 31

What happens to the **byproducts of fission** reactions?

Answer 31

They often release **radioactive radiation**. ## Footnote The radiation can remain for 1,000 to 10,000 years, which can pose a challenge to waste management.

Question 32

What is **thermal energy**?

Answer 32

The energy in an object or system due to the **movement of its molecules and atoms**. ## Footnote Thermal energy is often referred to as ‘heat energy.’

Question 33

What happens to particles as **thermal energy increases**?

Answer 33

They move faster. ## Footnote Higher energy levels correspond to increased particle motion.

Question 34

List the *three* methods of **heat transfer**.

Answer 34

1. Conduction 1. Convection 1. Radiation ## Footnote These describe the movement of thermal energy from a hotter object or system to a colder one.

Question 35

What is the **difference** between conduction and convection?

Answer 35

* **Conduction**: Thermal energy transfer in solids that are in physical contact. * **Convection**: Thermal energy transfer in fluids such as water and air. ## Footnote In conduction, faster particles collide with slower ones, transferring energy. In convection, warmer particles rise while cooler particles sink.

Question 36

Which heat transfer method is responsible for **keeping the Earth warm**?

Answer 36

Radiation ## Footnote It is a thermal energy transfer method in which energy moves through electromagnetic waves. Radiant heat from the sun reaches the Earth through electromagnetic waves.

Question 37

Why does a **metal feel colder than wood** at the same temperature?

Answer 37

A metal **conducts heat away from your hand faster** than wood. ## Footnote Good conductors transfer thermal energy efficiently. Metal is a good conductor while wood is a poor conductor.

Question 38

Why does **rubbing your hands** together warm them?

Answer 38

Due to **friction** which generates thermal energy. ## Footnote This is a form of conduction.

Question 39

Sate the **law of conservation of energy**.

Answer 39

Energy is **neither created nor destroyed**; it can change form but the total amount remains constant. ## Footnote Examples: * Potential energy being converted into kinetic energy. * Chemical energy being converted into mechanical energy.

Question 40

Which energy conversion happens when a person **eats food and moves**?

Answer 40

**Chemical** energy is converted into **mechanical** energy. ## Footnote This is an everyday example of potential energy changing form to kinetic energy. A similar energy conversion occurs in a car engine where chemical energy stored in gasoline is converted into mechanical energy.

Question 41

Describe energy conversion in **photosynthesis**.

Answer 41

**Thermal** energy from the sun is converted into **chemical** energy. ## Footnote The chemical energy is stored as glucose molecules. This is an example of kinetic energy changing form to potential energy.

Question 42

What type of energy conversion occurs in a **toaster**?

Answer 42

**Electrical** energy is converted into **thermal energy**. ## Footnote This is an everyday example of energy conversion between two types of kinetic energies.