Contact & Non-Contact Forces (Edexcel GCSE Physics): Revision Notes
📚 Revision Notes
5.1.2 Contact & Non-Contact Forces
Force
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A force is a push or pull that acts on an object due to interaction with another object. All forces have both magnitude and direction (vector quantity). Measured in Newtons.
Contact Forces
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Forces where the two objects are physically touching.
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Examples:
- Tension in a rope during tug of war.
- Friction.
- Air resistance in a skydiver:
- As the skydiver falls, air particles collide with the parachute.
- This causes the force of air resistance to act upwards.
Normal Contact Force
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Can only happen when two objects are in direct contact.
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Example:
- Lamp on a table:
- The lamp is exerting a downward force on the table which is its weight.
- At the same time, the table is exerting an upward force on the lamp called the normal contact force.
Non-Contact Forces
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Forces where the two objects are physically separated.
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Examples:
- Gravitational force:
- Attracts all objects to other objects (e.g., the ISS to Earth and the Earth to the ISS).
- Electrostatic force:
- The force between two charged objects.
- Oppositely charged = electrostatic force of attraction.
- Same charge = electrostatic force of repulsion.
- Magnetic force:
- The force experienced by certain objects in a magnetic field.
Object Interaction
- A force is a push or pull that acts on an object due to the interaction with another object. All forces between objects are either:
Non-Contact Forces
- The objects are physically separated.
- Electrostatic:
- The charges cause a force of attraction/repulsion.
- Gravitational Attraction:
- The mass creates a force of attraction.
Contact Forces
- The objects are physically touching.
- Normal Contact Force:
- Felt in the opposite direction to contact.
- The force is normal to the planes of contact.
- Friction:
- The surfaces and their roughness cause friction when moved in contact.