Year 8
Power and energy
Define power and its relationship to energy. Calculate power using energy and time.
Year 8
Power and energy
Define power and its relationship to energy. Calculate power using energy and time.
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Lesson details
Key learning points
- Explain the relationship between energy and power
- Convert between watts and kilowatts, and minutes and seconds
- Convert between minutes and seconds
Equipment
Calculator
Licence
This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.
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6 Questions
Q1.
Which two of the following are stores of energy?
electrical
light
Q2.
What is the unit of energy?
newton
volt
watt
Q3.
How many seconds are in a minute?
6
600
66
Q4.
Which is the correct order of energy stores for someone doing a bungee jump?
elastic potential → kinetic → gravitational potential
kinetic → gravitational potential → elastic potential
Q5.
Match each heat transfer method to the correct description.
energy is transferred by waves
occurs in liquid or gas
happens in solids
Q6.
Which of the following is used to reduce the rate at which heat is transferred in the home?
conduction
convection
radiation
6 Questions
Q1.
Power is the rate at which is transferred.
Q2.
Match each of the following to the correct units.
watts
joules
seconds
Q3.
How do you convert a value given in kilowatts to watts?
add 1,000
divide by 1,000
Q4.
How do you convert a time given in minutes to seconds?
add 60
divide by 60
subtract 60
Q5.
Calculate the power if 115 J of energy is transferred in 5 seconds.
0.043 W
23 kW
575 W
Q6.
Calculate the power of hair straighteners that use 16,000 joules of energy in 1 minute and 40 seconds.
100 watts
16 watts
160 kilowatts