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Oxford Insight Science 8

Jenny Zhang, Diane Alford, Samantha Hopley, Craig Tilley

Chapter 3

Energy - all with Video Answers

Educators


Chapter Questions

01:16

Problem 1

Fill in the gaps using the words in the Word Bank below:
Energy comes in many different forms, such as thermal, light, sound, ______________________ , electrical and potential energy. It cannot be created or ______________________ , but it can be transferred or ______________________ into a different type. Thermal energy can be ______________________ in three different ways: conduction, ______________________ and radiation. Electrical energy is transferred in electrical ______________________ and then transformed into almost any other form of energy by the ______________________ in the circuit. Most energy transformations also produce by-product energy, most commonly ______________________ , which reduces the ______________________ of the device. Scientific knowledge and technological developments have led to the improvement of energy efficiency, such as the invention of CFLs and ______________________ . Increased energy efficiency means less energy is ______________________ , which is ______________________ for individuals and better for the environment as fewer resources are consumed.
$$
\begin{array}{lll}
\text { circuits } & \text { efficiency } & \text { more economical } \\
\text { components } & \text { heat } & \text { transferred } \\
\text { convection } & \text { kinetic } & \text { transformed } \\
\text { destroyed } & \text { LEDs } & \text { wasted }
\end{array}
$$

Manne Andergronde
Manne Andergronde
Numerade Educator
04:30

Problem 2

Define the following terms and provide an example for each:
a gravitational potential energy
b biofuel
c kinetic energy.

Christopher Nilsen
Christopher Nilsen
Numerade Educator
00:13

Problem 3

Explain all the ways that energy can be stored.

Morgan Thompson
Morgan Thompson
Numerade Educator
01:57

Problem 4

Identify whether a spring or a string has more advantages for storing elastic potential energy. Explain your answer.

Manish Jain
Manish Jain
Numerade Educator
03:47

Problem 5

Compare an electric- to a petrol-driven car to answer the following questions:
a Identify the main energy transformations that occur in a petrol-powered car.
b Identify the main energy transformations that occur for an electric car.
c Identify the advantages and disadvantages of each type of car.
d Explain how hybrid cars are different from both petrol and electric cars.

Anand Jangid
Anand Jangid
Numerade Educator
00:36

Problem 6

Explain the difference between an energy flow diagram and an energy chain.

David Collins
David Collins
Numerade Educator
03:00

Problem 7

Identify a device that performs the following energy transformations and draw an energy flow diagram or energy chain as appropriate:
a light energy to sound energy
b kinetic energy to heat energy
c electrical energy to sound energy
d chemical potential energy to light energy.

Reed Mckee
Reed Mckee
Numerade Educator
04:10

Problem 8

Compare and contrast conduction, convection and radiation.

Devin Lea
Devin Lea
Numerade Educator
01:33

Problem 9

When a hot brick is placed into a bucket of water, the water gets hotter as thermal energy spreads from the brick into the water. Identify if this process is called conduction, convection or radiation. Explain your choice and why it is not the other options.

Ma Ednelyn Lim
Ma Ednelyn Lim
Numerade Educator
01:16

Problem 10

An electric kettle uses a heating element to heat water. This process involves both conduction and convection. Explain where each process occurs to heat the whole jug of water.

Adriano Chikande
Adriano Chikande
Numerade Educator
00:13

Problem 11

Define the term 'electrical energy'.

David Collins
David Collins
Numerade Educator
01:11

Problem 12

Describe why circuits are needed to transport electrical energy to components and devices.

Luis Rios
Luis Rios
Numerade Educator
01:38

Problem 13

Compare conduction of thermal energy with the transfer of electrical energy.

Victoria Jones
Victoria Jones
Numerade Educator
01:19

Problem 14

Explain why circuits are drawn as diagrams rather than as detailed pictures.

Manish Kumar
Manish Kumar
Numerade Educator
00:41

Problem 15

Draw a circuit diagram for a circuit that contains a power supply and three light globes in a parallel circuit, with a switch in series with one of the light globes.

Chinmai Managoli
Chinmai Managoli
Numerade Educator
01:08

Problem 16

Explain the difference between how two light bulbs in a series circuit and two bulbs in a parallel circuit are arranged.

Manish Kumar
Manish Kumar
Numerade Educator
03:33

Problem 17

Briefly describe the development of the light bulb and explain why these improvements have been made.

Aja S
Aja S
Numerade Educator
02:12

Problem 18

Explain why scientists and engineers continue to research the design of solar panels.

Jennifer Stoner
Jennifer Stoner
Numerade Educator
02:20

Problem 19

Draw an energy flow diagram for the following activities:
a hearing a loudspeaker
b using a hairdryer
c listening to an iPod
d using a microphone.

Vishal Gupta
Vishal Gupta
Numerade Educator
02:10

Problem 20

Explain how electrical energy is transformed and transported.

MM
Matthew Moffitt
Numerade Educator
02:17

Problem 21

Define the term 'by-product'.

Suman Saurav Thakur
Suman Saurav Thakur
Numerade Educator
02:19

Problem 22

List four different energy transformations that produce heat as a by-product.

Mir  Afzal
Mir Afzal
Numerade Educator
02:04

Problem 23

Calculate the percentage energy efficiency of a device that turns $200 \mathrm{~J}$ of input energy into $150 \mathrm{~J}$ of useful output energy.

Prabhu Ramji
Prabhu Ramji
Numerade Educator
00:38

Problem 24

What is the percentage efficiency for a device that transforms $40 \mathrm{~J}$ of energy into $30 \mathrm{~J}$ of useful sound energy and $10 \mathrm{~J}$ of wasted heat?

Zachary Warner
Zachary Warner
Numerade Educator
03:12

Problem 25

Explain why LEDs are becoming more commonly used than incandescent bulbs.

Ben Nicholson
Ben Nicholson
Numerade Educator
03:04

Problem 26

Compare LEDs, CFLs and incandescent bulbs in terms of their energy efficiency.

AG
Ankit Gupta
Numerade Educator
02:10

Problem 27

Solar panels for my house are too expensive and will cost me too much money in the long term'. Evaluate this statement and write a response to support or disagree with it.

David Collins
David Collins
Numerade Educator
01:32

Problem 28

Calculate the cost of running a 15-watt CFL light globe for 100000 hours if it costs $$\$ 4.00$$ for each bulb, the bulbs last 10000 hours each and electricity costs $$\$ 0.15$$ per kWh.

Ze-Han Lee
Ze-Han Lee
Numerade Educator
03:55

Problem 29

Is there an endless supply of energy on the Earth or do you think it will run out one day? Justify your answer.

Averell Hause
Averell Hause
Carnegie Mellon University
01:54

Problem 30

What are two major benefits wind power offers over conventional coalfired power stations?

Supratim Pal
Supratim Pal
Numerade Educator