Starter quiz
- Which properties of an object can be increased so it has more energy in its kinetic store?
- height
- mass ✓
- speed ✓
- temperature
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- Why does a shopping trolley that has been pushed and then let go of come to a stop?
- It runs out of energy.
- Energy is transferred to the surroundings. ✓
- A gravitational force pushes down on it.
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- What happens to the amount of work done moving a car, if the car is pushed with the same size force for three times the distance?
- One third of the work.
- The same amount of work.
- Three times the work. ✓
- Nine times the work.
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- In which of these situations does the applied force not do any work?
- Pushing a trolley forward to speed it up.
- Pushing a trolley forward against friction, to keep it at the same speed.
- Pushing down on a trolley as it moves forwards. ✓
- Pushing on a trolley backwards to slow it down.
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- How would you calculate the work done by a catapult in shooting a small ball forward?
- Work done = force of catapult × distance over which it pushes on the ball ✓
- Work done = force of catapult ÷ distance over which the ball moves
- Work done = force of catapult × mass of the ball
- Work done = force of catapult ÷ mass of the ball
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- A catapult does work on a small ball to fire it vertically up into the air. What is the amount of work done on the ball equal to?
- Energy in the kinetic store as the ball leaves the catapult. ✓
- Energy in the kinetic store at its highest point.
- The energy in the gravitational store when the ball leaves the catapult.
- Energy in the gravitational store at its highest point.
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Exit quiz
- How much energy will be transferred to the kinetic store if three times the amount of work is done on kicking a football?
- The same amount of energy.
- Three times as much energy. ✓
- Nine times as much energy.
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- If friction and air resistance are ignored, how much energy is dissipated by a toy car moving across a table?
- All of the car's energy.
- Most of the car's energy.
- A tiny amount of the car's energy.
- None of the car's energy. ✓
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- What happens to the amount of energy in the kinetic store of a ball if it is moving at two times the speed?
- The amount of energy in the kinetic store does not change.
- The amount of energy in the kinetic store is two times bigger.
- The amount of energy in the kinetic store is four times bigger. ✓
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- What is kinetic energy?
- The type of energy that is in the kinetic store.
- The type of energy an object has because it is moving.
- The amount of energy an object has that is in its kinetic store. ✓
- The total amount of energy that a moving object has.
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- What is the kinetic energy of a discus of mass 2 kg moving at a speed of 8 m/s?
- '64 J' ✓
- What is the mass of a javelin that has a kinetic energy of 72 J and a speed of 12 m/s?
- '1 kg' ✓
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Energy is measured in joules (J).
- Doubling the mass of a moving object doubles the energy it has in its kinetic store.
- Doubling the speed of an object increases the energy it has in its kinetic store by four times.
- The energy an object has in its kinetic store of energy is found using the equation Ek = ½ mv².
Common misconception
When calculating energy in the kinetic store, pupils often work out ½ mv and then square everything, rather than just the speed.
Scaffold calculations to show how kinetic energy is calculated, taking pupils through how to do this on their calculators without making a mistake.
Keywords
Work done - Work is done whenever a force makes an object move. The amount of work done is equal to the force multiplied by distance moved in the direction of the force.
Kinetic store - If an object is moving and has a mass, then there is energy in its kinetic store.
Directly proportional to - If two quantities are directly proportional, then as one increases, the other also increases at the same rate.
Kinetic energy - The energy an object has in its kinetic store is referred to as the object’s kinetic energy.
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