2C1 Energy

Question 1

Define:

energy

Answer 1

The ability to do work.

Energy can be categorized into potential and kinetic energy.

Work involves moving an object by force.

Question 2

Define:

potential energy

Answer 2

The stored energy in an object.

This energy may be the result of position, electric charge, or outside forces acting upon it.

Question 3

Define:

kinetic energy

Answer 3

The energy of a moving object or particle.

The amount of energy depends on mass and motion.

Question 4

List four types of potential energy.

Answer 4

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 5

Name five types of kinetic energy.

Answer 5

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

Kinetic energy is energy in motion.

Question 6

List three examples of kinetic energy.

Answer 6

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 7

List three examples of potential energy.

Answer 7

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 8

Fill in the blank:

Kinetic energy can be transferred, while potential energy _______.

Answer 8

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 9

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

Answer 9

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 10

What is a practical application of kinetic energy?

Answer 10

Wind turbines converting motion into electrical energy.

Wind turbines capture the kinetic energy of wind to spin their blades, which turn a generator to produce electricity. This is a well-established example of kinetic energy being transformed into another useful form.

Question 11

Fill in the blank:

A stretched rubber band has _______ energy.

Answer 11

potential

Elastic potential energy is stored in deformed objects and released when they return to their original shape.

Question 12

Define:

chemical energy

Answer 12

Energy stored in the bonds of chemical compounds.

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

Question 13

How is chemical energy used in batteries?

Answer 13

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

This process involves an anode and cathode.

Question 14

What is an example of chemical energy in daily life?

Answer 14

Burning wood

Burning wood is a chemical reaction known as combustion, where stored chemical energy in the wood reacts with oxygen to produce heat, light, carbon dioxide, and water vapor.

Question 15

What process do plants use to store chemical energy?

Answer 15

Photosynthesis

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

Question 16

What type of energy is carried by electromagnetic waves?

Answer 16

Light energy

Light (radiant) energy travels in waves and does not require a medium, unlike sound energy.

Question 17

True or False:

Sound energy can travel through space.

Answer 17

False

Sound energy travels as vibrations through a medium (solid, liquid, or gas). Unlike light waves, sound waves require a medium and cannot propagate in a vacuum.

Question 18

Fill in the blanks:

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

Answer 18

absorbed; released

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

Question 19

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

Answer 19

• Iron powder
• Water
• Salt
• Carbon

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

Question 20

What is the primary source of chemical energy in food?

Answer 20

Solar energy

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

Question 21

What form of energy results from the movement of electric charges?

Answer 21

Electrical energy

Electrical energy powers devices like light bulbs and motors, and is generated by sources like batteries or power plants.

Question 22

What is thermal energy?

Answer 22

Energy from the movement of molecules and atoms.

Thermal energy, often called heat energy, comes from the motion of particles within a substance.

Question 23

What is the role of electrons in electrical energy?

Answer 23

Moving electrons create electrical energy.

Electric fields influence movement.

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

Question 24

Define:

static electricity

Answer 24

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 25

List some **common units** of electrical energy.

Answer 25

* Ampere (A) * Coulomb (C) * Joule (J) * Watt (W) * Volt (V) * Kilowatt-hour (kWh) ## Footnote These units measure various electrical properties such as current, charge, energy, power, and potential difference.

Question 26

What is a **nuclear power plant**?

Answer 26

A facility that uses **nuclear reactions** to generate electricity. ## Footnote Nuclear power plants operate primarily through *controlled fission reactions*, where atomic nuclei split to release energy. The world’s first nuclear power plant switched on in **1951**. It powered four 200-watt light bulbs.

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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

Question 29

State the **law of conservation of energy**.

Answer 29

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 30

How does a **pendulum** show energy conservation?

Answer 30

Energy **shifts** between kinetic and potential forms. ## Footnote At the highest point, the pendulum has *maximum potential energy*. As it swings down, this energy transforms into *kinetic energy*, repeating the cycle until friction and air resistance gradually stop the motion.

Question 31

# True or False: A roller coaster needs a **constant energy** input to keep moving.

Answer 31

False ## Footnote A roller coaster moves by converting potential energy into kinetic energy *without needing* a continuous energy supply. After an initial energy boost (like a chain lift), gravity drives the motion, though friction and air resistance gradually slow it down.

Question 32

# True or False: In an ideal roller coaster, the total energy is **conserved** throughout the ride.

Answer 32

True ## Footnote In the absence of friction and air resistance, the total mechanical energy (kinetic + potential) remains **constant**.

Question 33

What **happens** to energy in a spring when compressed or stretched?

Answer 33

It stores **potential energy** when compressed or stretched. ## Footnote The energy stored in the spring is *elastic potential energy*, which is released when the spring returns to its original shape.

Question 34

What **happens** to energy when a moving car stops?

Answer 34

It **transforms** into heat and sound energy. ## Footnote The car’s kinetic energy is converted into thermal energy due to **friction** in brakes and sound energy due to road resistance.

Question 35

# True or False: **Energy is lost** in an open system.

Answer 35

False ## Footnote Energy is not lost but **converted** into less useful forms, like heat due to friction.

Question 36

What is **energy transfer**?

Answer 36

The **movement of energy** from one place or system to another. ## Footnote Energy transfer can occur through different processes like *heat transfer*, *work*, or *radiation*.

Question 37

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

Answer 37

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 38

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

Answer 38

* **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 39

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

Answer 39

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 40

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

Answer 40

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 41

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

Answer 41

Due to **friction** which generates thermal energy. ## Footnote When you rub your hands together, friction between your skin **converts** mechanical energy into heat (*thermal energy*). This heat is transferred to your hands through **conduction**, raising their temperature.

Question 42

List examples of **energy transformation**.

Answer 42

* A **toaster** converts electrical energy into thermal energy. * A **flashlight** converts chemical energy into light energy. * A **car engine** converts chemical energy into kinetic energy.

Question 43

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

Answer 43

**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 44

Describe energy conversion in **photosynthesis**.

Answer 44

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 45

What form of **energy conversion** occurs in solar panels?

Answer 45

Light energy to electrical energy. ## Footnote *Solar panels* use *photovoltaic cells* to convert sunlight into usable **electricity**.

Question 46

# True or False: A battery **transforms** electrical energy to chemical energy.

Answer 46

False ## Footnote A **battery** stores chemical energy that is later converted into electrical energy when in use.

Question 47

What is an **example** of electrical to mechanical energy transformation?

Answer 47

Electric motor ## Footnote In an *electric motor*, electrical energy is used to create a magnetic field, which moves a rotor and performs mechanical work.

Question 48

What role does a **generator** play in energy transformation?

Answer 48

It **converts** mechanical energy into electrical energy. ## Footnote In power plants, turbines driven by wind, water, or steam turn generators to produce electricity.

Question 49

# True or False: Electrical energy can be **easily transformed** into heat energy.

Answer 49

True ## Footnote Many *electrical devices*, such as electric heaters and toasters, convert electrical energy into heat energy to perform their functions.