♡ Topic 9_Forces and their effect ♡

• An alternative name for the turning effect of a force is a moment
• The equation used to calculate the moment of a force is: Moment of force = Force x Distance. The appropriate units are Moment (Nm), Force (N), Distance (m)
• The distance measurement used when calculating a moment is the perpendicular distance from the pivot to the line of action of the force
• If an object is in equilibrium, the moments acting on the object are such that the clockwise moments are equal to the anticlockwise moments
• Levers make use of moments by increasing the perpendicular distance of the force from the pivot, thereby decreasing the force needed to produce the same moment
• In the case of an object with forces of 20N and 10N acting at distances of 4m and 2m respectively, the object will not rotate as the clockwise and anticlockwise moments are equal, keeping the object in equilibrium
• Levers are used to decrease the force required to lift something by utilizing a pivot point and the concept of moments to reduce the force. The further away you are from the pivot point, the less force you need to lift the object up
• Lubricating levers/gears improves efficiency by reducing resistance, resulting in less energy wasted or dissipated (as heat) to overcome frictional forces
• Force: A push or pull acting on an object due to an interaction with another object
• Forces can be split into two categories:

  • Contact forces (objects touching)
  • Non-contact forces (objects separated)
• Examples of contact forces:

  1. Friction

  2. Air resistance

  3. Tension
• Examples of non-contact forces:

  1. Gravitational forces

  2. Electrostatic forces

  3. Magnetic forces
• Force is a vector quantity because:

  • It has both magnitude and direction
• Scalar quantity:

  • A quantity that only has a magnitude
  • A quantity that isn't direction dependent
• Vector quantity:

  • A quantity that has both magnitude and direction
• Examples of vector quantities:

  1. Velocity

  2. Displacement

  3. Force
• Examples of scalar quantities:

  • Temperature
  • Time
  • Mass
  • Speed
  • Distance
  • Energy
• Resultant force with higher magnitude:

  • 45N
• Vectors are represented by:

  • Vector arrows
  • Length indicates magnitude
  • Arrow indicates direction
• Calculating resultant magnitude and direction of forces using a scale drawing:

  1. Draw the component forces as scaled arrows, joined tip-to-tail

  2. Draw a line connecting the two open ends

  3. Measure the length of this line and convert into the magnitude

  4. Measure the angle between the resultant line and the vertical/horizontal to find the direction