Topic 5

• What is a moment in physics?

  Turning effect of a force
• What condition must be met for equilibrium?

  Clockwise moments = Anticlockwise moments
• What is the formula for moments?

  M = F d
• What do gears alter in a mechanical system?

  Force and speed
• How do levers function in mechanics?

  They act as force multipliers
• What are mechanical quantities classified into?

  Scalar and vector
• What is a resultant force?

  The sum of all forces acting on an object
• What does magnitude refer to in physics?

  Magnitude only
• What does a vector quantity include?

  Magnitude and an associated direction
• What is the centre of mass?

  Single point where weight acts
• How is weight measured?

  Using a Newtonmeter
• What does Hooke's Law state?

  Force is proportional to extension
• What is the limit of proportionality in Hooke's Law?

  Only up to the limit of proportionality
• What is the formula for Hooke's Law?

  F = k e
• When is work done on a spring?

  When stretched or compressed
• What is the formula for work done?

  W = F s
• What is the formula for elastic potential energy?

  E = 0.5 x k x e²
• How is 1 joule defined in terms of force?

  1 joule = 1 newton-metre
• What does 'k' represent in the elastic potential energy formula?

  Spring constant
• What is the formula for weight?

  W = mg
• What is momentum measured in?

  kgm/s
• What does the conservation of momentum state?

  Total momentum before and after is equal
• What is the formula for momentum?

  p = m v
• How is pressure defined in physics?

  Force per unit area
• How is pressure measured?

  In pascals
• What is upthrust?

  An upwards force on a submerged object
• What causes upthrust in a submerged object?

  Pressure below it
• What is atmospheric pressure?

  Thin layer of air around the Earth
• How is atmospheric pressure calculated?

  p = h ⍴ g
• How does pressure change with altitude?

  Pressure decreases with altitude
• What is Newton's 1st Law?

  An object remains at rest or constant velocity
• What is Newton's 2nd Law?

  F = m a
• What is Newton's 3rd Law?

  Every action has an equal and opposite reaction
• What is the difference between speed and velocity?

  Speed is scalar; velocity is vector
• What is the formula for speed?

  s = v t
• What is the formula for acceleration?

  a = Δv / t
• What does the gradient of a velocity-time graph represent?

  Gradient represents acceleration
• What does the gradient of a distance-time graph represent?

  Gradient = Speed
• What factors affect braking distance?

  Thinking distance + braking distance
• What is the average human reaction time?

  ~ 0.2-0.9 seconds