Forces

    Cards (164)

    • Force
      A push or pull that acts on an object due to its interaction with another object
    • Newtons
      The unit used to measure force
    • Forces
      • Have both magnitude (measured in newtons) and direction (e.g. to the right)
    • Vector quantities
      Quantities that have both magnitude and direction
    • Types of forces
      • Contact forces
      • Non-contact forces
    • Contact forces
      • Require the two objects to be physically touching
    • Normal contact force
      Also known as the reaction force, it is the equal and opposite force exerted by a surface to keep an object in position
    • Non-contact forces

      • Do not require the two objects to be touching
    • Types of non-contact forces
      • Gravitational force
      • Magnetic force
      • Electrostatic force
    • Fields of influence
      The surrounding area where non-contact forces can act on objects
    • As the distance between objects increases
      The strength of non-contact forces decreases
    • Scalar quantities

      Physical quantities that only have a magnitude but no direction
    • Magnitude
      Size, can be measured with a numerical value
    • Scalar quantities
      • Speed
      • Distance
      • Mass
      • Temperature
      • Time
    • Vector quantities

      Physical quantities that have both a magnitude and a direction
    • Vector quantities
      • Velocity
      • Displacement
      • Acceleration
      • Force
      • Momentum
    • Representing vectors
      1. Use arrows
      2. Length of arrow indicates magnitude
      3. Direction arrow is pointing indicates direction
    • Distance doesn't give any idea of direction, which is why it's a scalar quantity
    • Displacement has both a magnitude and a direction, which is why it's a vector quantity
    • Free body diagrams
      Simple diagrams that show all the forces that are acting on a particular object
    • Drawing free body diagrams
      1. Add force arrows to represent all the forces acting on an object
      2. Each force arrow has a magnitude and direction
    • Forces are vectors, so they have both magnitude and direction
    • Some forces will cancel each other out
    • Resultant force
      The overall force on an object after taking into account all the individual forces
    • Calculating the resultant force
      1. Look at the horizontal and vertical components separately
      2. Calculate the overall size and direction of the resultant force in each case
    • Calculating the resultant force
      • Vertical component: 80,000N up - 80,000N down = 0N resultant
      • Horizontal component: 120,000N right - 90,000N left = 30,000N resultant to the right
    • If air resistance is 120,000N
      Horizontal resultant force is 0N, object is in equilibrium
    • Scale drawing
      A drawing where the size of objects is proportional to their actual size
    • Finding resultant force on an object using scale drawings
      1. Represent forces as arrows
      2. Place arrows tip to tail
      3. Draw line from start to end
      4. Measure length of line
      5. Convert length to force using scale
    • Forces on a cyclist
      • 4 newtons northwards
      • 3 newtons eastwards
    • Resultant force
      Magnitude and direction
    • Resultant force is 5 newtons at 37 degrees from north
    • Forces balance
      Object is at equilibrium
    • Resolving vectors
      1. Draw horizontal and vertical components
      2. Measure lengths of components
      3. Convert lengths to forces using scale
    • Resolving 50 newton force on toy car up ramp

      • 40 newtons to the right
      • 30 newtons upwards
    • Different types of elasticity
      1. Explain
      2. Explain spring constant
      3. Explain Hooke's law
      4. Look at force extension graphs
    • Applying a force to an object
      Can cause it to compress, stretch or bend
    • Easiest to see with a spring, but same concept applies to other objects like a ball or a phone</b>
    • Other objects are less elastic, so harder to notice changes in shape
    • To stay still, need to apply more than one force
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