Physics

• Average speed


  total distance travelled ÷ total time
• Acceleration


  Change in velocity ÷ time taken

  m/s^2
• How to find the speed in a distance-time graph?

  Speed is the gradient of the line.

  
• How to find distance in a speed-time graph?

  Area under the graph shows total distance covered.

  
• Force =


  Mass x Acceleration

  N - Newtons
• Weight =


  Mass x Gravity

  
  

  N - Newtons

  
  

  Mass

  g, kg

  
  

  Gravity

  N/g, N/kg
• Terminal Velocity


  the constant maximum velocity reached by a body falling through the atmosphere under the attraction of gravity
• Moment


  Force x Perpendicular distance from pivot

  Nm
• Equilibrium


  All forces and moments are balanced
• Hooke's Law


  Material obeys Hooke's Law if the force-extension graph is linear
• Resultant force


  All forces added together
• Elastic


  Object can recover original shape once a deforming force is removed
• Speed, Distance and Time

  Speed = Distance ÷ Time

  m/s, km/hr, mph, Mach, knots, light speed

  
  

  Time = Distance ÷ Speed

  s, min, hr

  
  

  Distance = Speed x Time

  cm, m, km

  
• How do you determine distance travelled from a velocity-time graph?

  area under the graph
• What are the effects of a force?

  changes in speed, shape or direction
• What is friction?


  A force that opposes motion
• Describe the forces acting on falling objects and explain why they reach terminal velocity.

  When an object falls it will initially accelerate. The force caused by air resistance increases as the speed increases. Eventually air resistance will equal the force of gravity, the forces are balanced and the speed is constant (a.k.a. terminal velocity)
• What does 'stopping distance' include?

  thinking distance and braking distance
• what factors affect thinking distance?

  speed, tiredness, alcohol, medication, level of concentration
• What factors affect braking distance?

  speed, tyres, brakes, road conditions, mass of car
• What is the centre of mass/gravity?


  The point where all the mass of the object is concentrated.
• moment =


  force x distance
• What is Hooke's law?

  When a spring stretches, the extension of the spring is proportional to the force stretching it, provided the elastic limit of the spring is not exceeded.
• What is elastic behaviour?


  The ability of a material to recover its original shape after the forces causing deformation have been removed.
• What do comets orbit?

  The sun!
• Describe the orbit of a comet.

  A comet has an elliptical orbit that causes the speed to increase closer to the sun due to gravity (they can only be seen close to the sun).
• How do planets orbit the sun?

  Circular orbit
• Displacement


  The distance travelled in a specific direction.
• Velocity


  Speed in a specified direction. Measured in m/s/s.
• Gradient


  Slope which gives speed on a distance-time graph.
• Straight lines


  Lines that mean constant speed on a distance-time graph.
• Area under the graph


  Area which shows distance travelled on a velocity-time graph.
• Define Weight


  Weight is the force that acts on a body because of gravity. Measured in Newtons (N).
• Friction


  The force that opposes motion, either when you try to make something move or whilst it is moving.
• Air resistance


  Friction between an object and the air (or gas) that is moving through.
• Upthrust


  The upward force that liquids and gases exert on objects.
• Magnetic


  Forces that magnets exert on other magnets or things made of iron.
• Electrostatic


  The force between electrically charged objects.
• Normal reaction


  The special name for the contact force that acts on an object pressing down on another object.
• Tension


  In strings, cables, ropes, etc. that are being stretched.