(c) Forces, Movement, Shape and Momentum

• A force can cause an object to change speed, direction or shape
• A resultant force is the net force that describes all of the forces operating on a body

  
• Friction is a force which opposes the motion of an object
• Weight is the force experienced by an object with mass when placed in a gravitational field
• The stopping distance of a car is the total distance travelled during the time it takes to stop in an emergency
• Thinking distance is the distance travelled in the time it takes the driver to react to an emergency and prepare to stop
• Thinking distance is dependent on tiredness, distraction and intoxication
• Stopping distance is dependent on road conditions, tyre conditions, brake conditions and mass of vehicle
• Stopping distance = Thinking distance + Braking distance