Forces and motion

• What is the equation for calculation speed?

  Speed = Distance/Time
• What is the difference between speed and velocity?

  Speed only has size (scalar), velocity is speed in a particular direction (vector).
• What are typical speeds for walking, running and cycling?

  1.5 m/s, 3 m/s, 6 m/s respectively.
• How can you calculate speed from a distance-time graph?

  Gradient (change in y/change in x)
• What is acceleration?

  Change in velocity (could be change in speed and/or direction).
• What is the unit for acceleration?

  m/s^2
• What is the acceleration of a free falling object due to gravity?

  9.8 m/s^2
• What is the equation which links acceleration, change in velocity and time?

  Acceleration(m/s^2) = change in velocity(m/s)/time(s)

  $a=$$Δv/t$
• How can you calculate acceleration from a velocity-time graph?

  Gradient(Δy/Δx)
• How can you calculate distance travelled from a velocity-time graph?

  area under the line.
• What is the equation that links acceleration, force and mass?

  Force(N) = mass(kg) x acceleration(m/s^2)

  F = ma
• What is the name of the tendency of an object to remain in a steady state (at rest or moving at the same speed and direction)?

  Inertia
• What is the inertial mass of an object?

  How difficult it is to change an object's velocity.
• What does the acceleration of an object depend on?

  $F=$$ma$

  Acceleration is directly proportional to force.

  Acceleration is indirectly proportional to mass.
• What does Newton's first law state regarding objects with no resultant force (balanced) acting on them?

  Object will remain still or moving at a constant speed in a constant direction.
• What does Newton's second law state regarding objects with a resultant force (unbalanced) acting on them?

  Object will change speed and/or direction.
• What does Newton's third law state?

  When two objects interact they exert equal and opposite forces on each other.
• What is the name of the frictional force acting on a moving force?

  Drag.
• In which direction does drag act on an object?

  In opposite direction to movement.
• What happens to drag force when speed increases?

  Drag increases.
• What effect does a larger surface area have on drag?

  increases drag.
• If an object is moving at a constant speed, what does this tell us about the forces acting on object?

  Forces are balanced (drag force = driving force/weight)
• What is the name of the maximum constant speed reached by falling/moving objects because drag force = weight/driving force?

  Terminal velocity.
• What can be done to reduce drag?

  Streamlining.