AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
Examples of contact forces include friction, air resistance, tension and…
Full specification wording
Contact and non-contact forces: Examples of contact forces include friction, air resistance, tension and normal contact force.
Contact forces need the two objects to be touching.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 2 of 5
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Contact forces need the two objects to be touching. Friction acts along the surfaces where two objects slide or try to slide past each other, always opposing the relative motion. Air resistance, and water resistance, are the friction of a fluid on an object moving through it, and grow larger as the object speeds up. Tension is the pull along a stretched rope, cable or spring, pulling inwards on whatever is attached at each end. The normal contact force is the push of a surface on an object resting against it, acting at right angles to that surface. Upthrust, the upward push of a fluid on an immersed object, is also a contact force and is accepted in answers.
What earns the marks
- A named contact force other than those already given in the question, such as tension, normal contact force or upthrust.
- The two objects being physically in contact while the force acts.
- Using the full name, normal contact force or normal reaction force, rather than 'reaction' alone.
- Identifying every contact force acting in a described situation, such as upthrust and normal contact force on a brick lying on the bottom of a pool.
Common mistakes and how to put them right
Answering 'drag', which examiners ignore because it repeats air resistance already given.
Offering gravity or weight, which are non-contact forces.
Writing 'reaction' on its own instead of normal contact force.
Describing friction as a force that acts in the direction of motion.
Leaving upthrust out when listing the forces on a submerged object.
Exam tips
- Check which forces the question has already named, because repeating one of them scores nothing.
- Lift, thrust and water resistance are all accepted, so you have more than three safe answers available.
- Say 'normal contact force' in full; it takes two extra words and secures the mark.
Try the lesson
The start of the Contact and non-contact forces: Examples of contact forces include friction, air resistance, tension and normal contact force. lesson, made from checked teaching notes for this specification point.
Have a go first
A box slides across a floor and slows down because the floor rubs against it. Which contact force causes this?
Listen
Contact forces need the two objects to be touching. Friction acts along the surfaces where two objects slide or try to slide past each other, always opposing the relative motion. Air resistance, and water resistance, are the friction of a fluid on an object moving through it, and grow larger as the object speeds up. Tension is the pull along a stretched rope, cable or spring, pulling inwards on whatever is attached at each end. The normal contact force is the push of a surface on an object resting against it, acting at right angles to that surface. Upthrust, the upward push of a fluid on an immersed object, is also a contact force and is accepted in answers. A strong answer earns marks for these points. a named contact force other than those already given in the question, such as tension, normal contact force or upthrust. the two objects being physically in contact while the force acts. using the full name, normal contact force or normal reaction force, rather than 'reaction' alone. identifying every contact force acting in a described situation, such as upthrust and normal contact force on a brick lying on the bottom of a pool. Exam tip: Check which forces the question has already named, because repeating one of them scores nothing.
Key words
Say what each word means before you turn the card.
friction
Try answering aloud or in your head before turning the card.
air and water resistance
Try answering aloud or in your head before turning the card.
tension
Try answering aloud or in your head before turning the card.
normal contact force
Try answering aloud or in your head before turning the card.
See every definition
- friction
- Acts along the surfaces where two objects slide or try to slide past each other, always opposing the relative motion.
- air and water resistance
- The friction of a fluid on an object moving through it, growing larger as the object speeds up.
- tension
- The pull along a stretched rope, cable or spring, pulling inwards on whatever is attached at each end.
- normal contact force
- The push of a surface on an object resting against it, acting at right angles to that surface.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Contact and non-contact forces: Examples of contact forces include friction, air resistance, tension and normal contact force.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge