Energy test
21 important questions on Energy test
What percentage of air consists of oxygen?
- Oxygen: 20%
What three things are required for combustion?
- Flame/fuel
- Oxygen
- Heat
Give an example of input and output energy using a battery-powered toy.
- Input: Batteries in the toy.
- Output: Toy moves or makes sounds.
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What is required to start burning fuels?
- Fuels need energy to start burning.
- Example: A burning match provides input energy.
Explain input and output energy using food.
- Input: Food consumed.
- Output: Energy for running, playing, doing things.
What is coal and how is it formed?
- Coal: a fossil fuel from ancient plants.
- Formed under Earth's pressure.
- Plants buried and transformed over time.
How does burning fuel release energy?
- Unlocks stored energy
- Molecules react with oxygen
- Releases heat and light
What happens when fuels start burning?
- Stored energy is released.
- Energy changes to heat and light.
What is the useful output energy of coal?
- Used for: Cooking, electricity.
- Output: Heat energy.
What type of energy do petrol and diesel provide to cars?
- Cars receive energy from
- Petrol
- Diesel
- This enables them to move.
How do different fuels release energy?
- Different amounts of energy stored
- Gasoline releases quickly
- Wood or coal release slowly, steadily
How does food provide energy to humans?
- Humans gain energy from food
- Helps them
- Function
- Grow
- Move
What happens when we use fuels?
- Tap into stored energy
- Power cars, heat homes
- Unlock fuel molecules
What are the uses and output energy of wood?
- Used for: Heating, cooking.
- Output: Heat energy.
What energy transformation occurs in candles?
- Candles produce
- Heat energy
- Light energy
- Convert stored chemical energy.
How does paraffin work when heated?
- Heat melts paraffin to gas.
- Gas burns to create a flame.
- Used in lamps and stoves.
Describe uses and output energy of petrol.
- Used for: Fueling vehicles.
- Output: Mechanical energy.
How does fire contribute to cooking?
- Fire produces heat energy
- Used to cook food on a braai.
What happens when wax melts?
- Melts into liquid when warm.
- Liquid travels up wick.
- Turns to gas, creating flame.
How do fuels store energy?
- Ingredients storing energy
- Used by cars, jets, and machines
What is gas and its property?
- No shape or size.
- Burns to release energy.
- Provides heat and light.
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