Forces

• Newton's 1st Law states that if an objects resultant force is 0, then that object is either stationary, or moving at a constant velocity
• Newton's 2nd Law states that an objects acceleration is directly proportional to the force applied to it, and inversely proportional to its mass (Force = Mass x Acceleration)
• Newton's 3rd law states that when two objects interact with one another, they exert equal but opposite forces on each other.
• Examples of Non-Contact forces are:

  -Magnetism

  -Weight/The Force Of Gravity

  -Electrostatic Force
• A vector quantity has both magnitude and direction
• A scalar quantity only has Magnitude
• Examples of Contact forces are:

  -Tension

  -Air Resistance

  -Water Resistance

  -Normal Contact Force

  -Upthrust

  -Friction
• Elastic Deformation: The object returns to its original state when the force is removed
• Plastic Deformation: The object does not return to its original shape when the force is removed
• Hooke's Law states that the extension of an object is directly proportional to the force applied to it, provided that the limit of proportionality is not exceeded
• Archimedes' Principle: Upthrust = Weight of water displaced
• Spring Extension Required Practical

  1. Set up a clamp stand with a clamp

  2. Hang the spring from the clamp

  3. Use a second clamp and boss to fix a (half) metre rule alongside the spring

  4. Record the ruler reading that is level with the bottom of the spring

  5. Hang a 1 N / a known weight from the bottom of the spring

  6. Record the new position of the bottom of the spring

  7. Calculate the extension of the spring

  8. Measure the extension of the spring

  9. Add further weights to the spring so the force increases 1 N at a time up to 5 N

  10. For each new force record the position of the bottom of the spring and calculate / measure the extension
• Circular Motion Around An Object

  -(a force) acts on the (object) causing it to accelerate towards (whatever is in the centre)

  -This changes the direction of motion, but not the speed.

  -Therefore the velocity of (object) changes
• Closed System: The total amount of energy in a system is constant
• Newton's Third Law: The force on A from B is equal and opposite to the force on B from A