applications of forces

• state Hooke's Law

  the extension of a spring is directly proportional to the force applied, provided that the limit of proportionality has not yet been reached.
• what is the equation used for obeying Hooke's law?

  F = ke
• what does each letter stand for?

  F = applied force (N)

  k = spring constant (N/m)

  e = extension (m)
• how do you calculate the spring constant from a force- extension graph?

  spring constant = gradient of a force-extension graph
• what is the definition of pressure?

  pressure is the force exerted per unit area
• equation used for pressure


  P = F/A
• what do each letter represent


  P = pressure (N/m²)

  F = Force (N)

  A = area (m²)
• what is 1 Pascal an equivalent unit for?

  1 Pa = 1 N/m²
• how do you increase pressure?

  • increase the force
  • decrease the area
• how do you decrease pressure?

  • decrease the force
  • increase the area
• what is the definition of centre of gravity?

  the centre of gravity of an object is the point where all of the weight of the object can be considered as acting
• where is the c.o.g?

  at the centre of the object
• equation for moment of a force


  M = F x D
• what do each letter represent


  M = moment (Nm)

  F = force (N)

  d = perpendicular distance between force and pivot (m)
• state the principle of moments 


  for an object to be balanced the sum of the clockwise moments about a point must be equal the sum of the anti-clockwise moments about that point