Starter quiz
- What is the difference between scalar quantities and vector quantities?
- Both have direction, but scalar quantities also have magnitude.
- Both have magnitude, but scalar quantities also have direction.
- Both have magnitude, but vector quantities also have direction. ✓
- Both have direction, but vector quantities also have magnitude.
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- Which of the following are vector quantities?
- speed
- energy
- velocity ✓
- distance
- displacement ✓
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- What is the meaning of the prefix ‘m’ in the units mm and mg?
- milli- ✓
- micro-
- thousandth ✓
- thousand
- millionth
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- What is the meaning of the prefix ‘k’ in the units km and kg?
- kine-
- kilo- ✓
- thousandth
- thousand ✓
- hundred
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- What is the meaning of the prefix ‘M’ in the units MW and MJ?
- mega- ✓
- micro-
- hundred
- millionth
- million ✓
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- Which of the following lengths are equal to 8.2 m?
- 820 mm
- 8200 mm ✓
- 82 mm
- 0.0082 km ✓
- 0.082 km
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Exit quiz
- Match the following key terms to their definition.
- resultant force⇔one force representing the overall effect of all forces on an object ✓
- contact force⇔a force that exists between objects only when they are touching ✓
- non-contact force⇔a force that exists between objects even if they are not touching ✓
- A block rests on a table. Which of the following diagrams correctly shows the weight of the block?
A footballer kicks a football. Which of the following diagrams correctly shows the force of the boot on the football?- Newton’s Third Law explains that interactions can be described by a pair of forces, sometimes called a ‘third law pair’. Which of the following are characteristics of the forces in a third law pair?
- They act between two objects only. ✓
- They act in the same direction.
- They are the same type of force. ✓
- They are the same size. ✓
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- A block rests on a table. Which of the following is the correct free body diagram for the block?
The diagram shows a ball hanging from a spring without moving. Two forces are shown. Which of the following statements are correct?- This is a free body diagram of the ball. ✓
- This is not a free body diagram of the ball.
- The two forces are a third law pair.
- The two forces are not a third law pair. ✓
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Some forces require contact between objects, while others do not.
- Forces are vectors and can be drawn as arrows on diagrams.
- A free body diagram shows all of the forces acting on a single object.
- For every force there is an equal sized force acting in the opposite direction.
- Force pairs have the same magnitude and type, and act in opposite directions between two objects.
Common misconception
Pupils may regard force as a property of an object, expressing ideas such as ‘the object has a force’ and ‘the object runs out of force’.
Describe forces as interactions between two objects, using the phrasing ‘the force of object A on object B’.
Keywords
Non-contact force - A force that exists between objects, even if they are not touching.
Contact force - A force that exists between objects when they are touching.
Normal contact force - The overall effect of a set of forces acting on an object is represented by a single resultant force.
Free body diagram - A diagram showing all of the forces acting on a single object.
Newton’s third law - Forces come in equal and opposite pairs, which act on pairs of different objects.
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