Topic 2

• The acceleration, g, experienced by an object travelling in free-fall. Its value at the surface of Earth is 10 m/s^2.

  Acceleration due to Gravity
• The rate of change in velocity. It can be calculated from the gradient of a velocity-time graph.

  Acceleration
• The distance a vehicle travels under braking force. This can be affected by adverse road and weather conditions as well as the condition of the vehicle.

  Braking Distance
• The resultant force that acts towards the centre of the circular path of an object travelling with circular motion.

  Centripetal force
• The motion of an object travelling in a circle. An object travelling in circular motion is always accelerating due to its continual direction change. This means that a centripetal force is always required.

  Circular motion
• The total momentum of a system before an event is always equal to the total moment of the system after the event.

  Conservation of momentum
• A measure of how fare an object moves in a given direction. It is the straight line between the starting and finishing points and is a vector quantity.

  Displacement
• Motion under the force of gravity alone.

  Free-Fall
• The time it takes for the brain to react to a stimulus, typically between 0.2-0.9 seconds.

  Human Reaction Time
• A measure of how hard it is to change an object’s velocity. It equals the ratio of force over acceleration.

  Inertial Mass
• An object’s acceleration is directly proportional to the resultant force acting on it.

  Newton’s Second Law
• The single force that can replace all the individual forces acting on an object, and have the same effect.

  Resultant force
• The distance a vehicle travels during the driver’s reaction time. This reaction time may be affected by tiredness, drugs or alcohol.

  Thinking distance