4.1.1 Energy Changes in a System

Question 1

What is a system?

Answer 1

An object or group of objects.

Question 2

How does energy storage change when a system changes?

Answer 2

The way energy is stored changes.

Question 3

Give an example of energy changes in systems.

Answer 3

Examples include:
* Object projected upwards
* Moving object hitting an obstacle
* Object accelerated by a constant force
* Vehicle slowing down
* Boiling water in a kettle

Question 4

What are ways energy changes occur?

Answer 4

Ways include:
* Heating
* Work done by forces
* Work done when a current flows

Question 5

What is the relationship between energy transfer and current flow?

Answer 5

Energy transfer and current flow are linked in circuits.

Question 6

What is the equation for kinetic energy?

Answer 6

𝐸𝑘 = 1/2 𝑚𝑣²

Question 7

In the kinetic energy equation, what does 𝐸𝑘 represent?

Answer 7

Kinetic energy (Joules, J)

Question 8

What does ‘m’ represent in the kinetic energy equation?

Answer 8

Mass (kg)

Question 9

What does ‘v’ represent in the kinetic energy equation?

Answer 9

Speed (m/s)

Question 10

What is the equation for elastic potential energy?

Answer 10

𝐸𝑒 = 1/2 𝑘𝑒²

Question 11

In the elastic potential energy equation, what does 𝐸𝑒 represent?

Answer 11

Elastic potential energy (J)

Question 12

What does ‘k’ represent in the elastic potential energy equation?

Answer 12

Spring constant (N/m)

Question 13

What does ‘e’ represent in the elastic potential energy equation?

Answer 13

Extension (m)

Question 14

What is the equation for gravitational potential energy?

Answer 14

𝐸𝑝 = 𝑚𝑔ℎ

Question 15

In the gravitational potential energy equation, what does 𝐸𝑝 represent?

Answer 15

Gravitational potential energy (J)

Question 16

What does ‘g’ represent in the gravitational potential energy equation?

Answer 16

Gravitational field strength (N/kg)

Question 17

What does ‘h’ represent in the gravitational potential energy equation?

Answer 17

Height (m)

Question 18

What is the equation for thermal energy change?

Answer 18

Δ𝐸 = 𝑚𝑐Δ𝜃

Question 19

In the thermal energy change equation, what does Δ𝐸 represent?

Answer 19

Change in thermal energy (J)

Question 20

What does ‘c’ represent in the thermal energy change equation?

Answer 20

Specific heat capacity (J/kg°C)

Question 21

What does Δ𝜃 represent in the thermal energy change equation?

Answer 21

Temperature change (°C)

Question 22

What is specific heat capacity?

Answer 22

Energy required to raise the temperature of 1 kg of a substance by 1°C.

Question 23

What is the power equation related to energy?

Answer 23

𝑃 = 𝐸/𝑡

Question 24

What is the power equation related to work done?

Answer 24

𝑃 = 𝑊/𝑡

Question 25

In the power equation, what does P represent?

Answer 25

Power (W)

Question 26

What does E represent in the power equation?

Answer 26

Energy transferred (J)

Question 27

What does W represent in the power equation?

Answer 27

Work done (J)

Question 28

What does t represent in the power equation?

Answer 28

Time (s)

Question 29

True or False: 1 joule per second equals 1 watt.

Answer 29

True

Question 30

What is a practical investigation related to energy transfer?

Answer 30

Investigate transfer of energy from gravitational potential to kinetic energy.

Question 31

What is a required practical regarding specific heat capacity?

Answer 31

Investigate specific heat capacity of materials by measuring temperature changes and energy transfers.