Quick answer: Energy is the ability to make things change, and it is measured in joules (J). This grade 6 science worksheet on forms of energy gives 20 problems from easy to hard: name the form, joules and renewable or not?. The worked answers are on a separate page, and the worksheet is a free printable PDF.
These problems train you to name the forms of energy, follow energy chains, calculate wasted energy and useful percentages, and compare renewable and non-renewable sources. They move from naming forms to multi-step calculations and decisions.
The worksheet suits grade 6, Year 7 and Class 6 students following NGSS middle school energy topics or similar curricula.
Level: Grade 6 science (Year 7 · Class 6) · Curriculum: MS-PS3
Problem 1 Name the form ★★★
Name the main form of energy in each case.1. A cricket ball flying towards the wicket.
2. A cup of hot soup.
3. The Sun shining on a window.
4. Current flowing in a phone cable.
5. A bowl of rice before it is eaten.
Problem 2 Joules ★★★
1. Name the SI unit of energy and give its symbol.2. Then convert 2.5 kJ into joules.
3. Finally, convert 4000 J into kilojoules.
Problem 3 Renewable or not? ★★★
Sort these sources into renewable and non-renewable: coal, wind, biogas, natural gas, sunlight, oil.Problem 4 A battery fan ★★★
Wanjiru uses a battery-powered hand fan on a hot day in Nairobi.1. Name the form of energy stored in the battery.
2. Then name the form of energy in the wires.
3. Finally, name the main useful form of energy given out by the fan blades.
Problem 5 Wind turbine chain ★★★
The figure shows the stages of a wind turbine that lights a lamp.2. Then name the form at stage B.
3. Next, name the form at stage C.
4. Finally, name the useful form given out by the lamp at stage D.
Problem 6 Law of conservation ★★★
Aarav says: “My torch battery is flat, so the energy has disappeared.”1. State the law of conservation of energy.
2. Then explain where the energy of the battery went.
Problem 7 Wasted energy of a lamp ★★★
A filament lamp in a classroom in Pune takes in 60 J of electrical energy every second and gives out 6 J of light.1. Calculate the wasted energy each second.
2. Then name the form of the wasted energy.
Problem 8 Useful percentage ★★★
A filament lamp transforms 100 J of electrical energy into 10 J of light. An LED lamp transforms 10 J into 8 J of light.1. Calculate the useful percentage of each lamp.
2. Then state which lamp wastes less energy.
Problem 9 Comparing appliances ★★★
The table shows the energy in and the useful energy out for three devices.| Device | Energy in (J) | Useful energy out (J) |
|---|---|---|
| Electric kettle | 1000 | 900 |
| Phone charger | 50 | 40 |
| Small motor | 200 | 150 |
2. Then calculate the useful percentage of each device.
3. Finally, state which device is the most efficient.
Problem 10 More kinetic energy ★★★
Compare the kinetic energy in each pair.1. A cyclist moving at 5 m/s and the same cyclist moving at 10 m/s.
2. A loaded truck and a bicycle, both moving at 5 m/s.
Problem 11 Bicycle dynamo ★★★
On a night ride in Kampala, Hina notices that her bicycle lamp gets brighter when she pedals faster.1. Write the energy chain from her muscles to the lamp.
2. Then explain why the lamp is brighter at higher speed.
Problem 12 Motorbike engine ★★★
The figure shows the energy flow in a motorbike engine.2. Then calculate the useful percentage of the engine.
3. Finally, describe what happens to the thermal energy.
Problem 13 Sources of electricity ★★★
The table shows the electricity produced in one year by a small country.| Source | Energy produced (units) |
|---|---|
| Hydro | 30 |
| Wind | 15 |
| Solar | 5 |
| Coal | 35 |
| Natural gas | 15 |
2. Then calculate the percentage that comes from renewable sources.
3. Finally, name one non-renewable source in the table.
Problem 14 Spot the error ★★★
Diego writes: “A solar panel makes energy from nothing.”1. Explain what is wrong.
2. Then write a correct statement.
Problem 15 Solar charger ★★★
A small solar charger receives 20 J of light energy every second and delivers 4 J of electrical energy every second.1. Calculate its useful percentage.
2. Then calculate the electrical energy it delivers in 60 s.
Problem 16 Two-stage chain ★★★
In a power station, 100 J of chemical energy in coal produces 40 J of electrical energy. An LED lamp then turns 80 % of the electrical energy into light.1. Calculate the light energy produced.
2. Then calculate the overall useful percentage from coal to light.
3. Finally, calculate the total energy that ends up as thermal energy.
Problem 17 Saving energy with LEDs ★★★
A filament lamp and an LED lamp both give out 6 J of light each second. The filament lamp takes in 60 J each second, the LED lamp 7.5 J each second.1. Calculate the useful percentage of the LED lamp.
2. Then calculate the energy each lamp takes in during one hour (3600 s) in kilojoules.
3. Finally, calculate the energy saved in one hour by using the LED lamp.
Problem 18 Missing energy in a phone ★★★
The figure shows how a phone transforms 100 J of battery energy.2. Then calculate the percentage of the battery energy that becomes useful light and sound.
3. Finally, explain why the phone feels warm.
Problem 19 Power for a farm ★★★
A farming community in Uganda needs electricity for lamps and a water pump. Sunshine lasts about 6 hours per day. A diesel generator needs fuel that must be bought and carried to the village. Wind is weak most of the year.1. Recommend one energy source and give two reasons.
2. Then suggest how the community can have light at night with your choice.
Problem 20 Food energy on a ride ★★★
One banana stores 400 kJ of chemical energy. Aarav’s muscles transform 25 % of the food energy into kinetic energy for cycling, and the rest into thermal energy.1. Calculate the kinetic energy produced from one banana.
2. Then calculate the thermal energy produced.
3. Finally, calculate how many bananas Aarav needs for 500 kJ of kinetic energy.
