AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Weight is the force acting on an object due to gravity. The force of…
Full specification wording
Gravity: Weight is the force acting on an object due to gravity. The force of gravity close to the Earth is due to the gravitational field around the Earth.
Weight is a force, measured in newtons (N), that acts on an object because of gravity.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 1 of 11
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Weight is a force, measured in newtons (N), that acts on an object because of gravity. It is not the same as mass, which is measured in kilograms (kg) and is the amount of matter in the object. Close to the Earth, the gravitational field around the Earth pulls objects towards the Earth's centre. The strength of this field near the surface is about 9.8 N/kg, often rounded to 10 N/kg in calculations. For example, a 2 kg mass has a weight of about 20 N on Earth because W = m × g = 2 kg × 10 N/kg = 20 N. Weight is a vector quantity: it has both magnitude and direction, and its direction is towards the centre of the Earth. The gravitational field is the region around the Earth where a mass experiences a force.
What earns the marks
- Weight is a force, so it is measured in newtons (N), not kilograms (kg).
- Weight acts on an object because of gravity, and its direction is towards the centre of the Earth.
- Mass is the amount of matter in an object and is measured in kilograms (kg); it is not the same as weight.
- The gravitational field around the Earth is the region where a mass experiences a gravitational force.
- Close to the Earth, the gravitational field strength is about 9.8 N/kg, often approximated as 10 N/kg for calculations.
- Weight can be calculated using W = m × g, where m is mass in kg and g is gravitational field strength in N/kg.
Common mistakes and how to put them right
Confusing weight with mass.
Put it right: Check the unit and the quantity being asked for.
Thinking weight is a scalar.
Put it right: Treat weight as a vector and state its direction when needed.
Using g = 10 N/kg as an exact value in all contexts.
Put it right: Use 9.8 N/kg unless the question says to use 10 N/kg.
Exam tips
- Read the question carefully to see whether it asks for mass or weight, and give the correct unit.
- When calculating weight, write the equation W = m × g, substitute values with units, and give the answer in newtons.
- If asked to explain gravity close to the Earth, mention the Earth's gravitational field and that it pulls objects towards the Earth's centre.
Try the lesson
The start of the Gravity: Weight is the force acting on an object due to gravity. The force of gravity close to the Earth is due to the gravitational field around the Earth. lesson, made from checked teaching notes for this specification point.
Have a go first
Which quantity is the force acting on an object due to gravity?
Listen
Weight is a force, measured in newtons (N), that acts on an object because of gravity. It is not the same as mass, which is measured in kilograms (kg) and is the amount of matter in the object. Close to the Earth, the gravitational field around the Earth pulls objects towards the Earth's centre. The strength of this field near the surface is about 9.8 N/kg, often rounded to 10 N/kg in calculations. For example, a 2 kg mass has a weight of about 20 N on Earth because W = m × g = 2 kg × 10 N/kg = 20 N. Weight is a vector quantity: it has both magnitude and direction, and its direction is towards the centre of the Earth. The gravitational field is the region around the Earth where a mass experiences a force. A strong answer earns marks for these points. Weight is a force, so it is measured in newtons (N), not kilograms (kg). Weight acts on an object because of gravity, and its direction is towards the centre of the Earth. Mass is the amount of matter in an object and is measured in kilograms (kg); it is not the same as weight. The gravitational field around the Earth is the region where a mass experiences a gravitational force. A common slip: Confusing weight with mass: weight is a force in newtons, while mass is in kilograms. Instead, check the unit and the quantity being asked for. Exam tip: Read the question carefully to see whether it asks for mass or weight, and give the correct unit.
See it
Key words
Say what each word means before you turn the card.
Weight
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Mass
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Gravitational field
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Vector quantity
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See every definition
- Weight
- The force acting on an object due to gravity, measured in newtons (N).
- Mass
- The amount of matter in an object, measured in kilograms (kg), and not the same as weight.
- Gravitational field
- The region around the Earth where a mass experiences a force.
- Vector quantity
- A quantity that has both magnitude and direction, with weight's direction being towards the centre of the Earth.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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