Newton's Laws of Motion

• Inertia is the tendency of an object to remain in a steady state.
• Newton's First Law:

  The velocity of an object will only change if a resultant force is acting on it.
• The resultant force on an object that is stationary or moving at a steady speed in a straight line is zero.
• An object will experience acceleration or deceleration if there is a resultant force that is not zero acting upon it.
• Resistive forces = driving forces when an object travels at a steady speed.
• Newton's Second Law:

  The acceleration of an object is proportional to the force on the object and inversely proportional to the mass of the object.

  F = m a
• The inertial mass of an object is how difficult it is to change an object's velocity.
• Newton's Third Law:

  When two objects interact, they exert equal and opposite forces on each other.
• Stopping distance is the distance a vehicle travels to safely come to a stop after the driver has spotted a hazard.
• Thinking distance is the distance a vehicle travels during the driver's reaction time.
• Braking distance is the distance a vehicle travels once brakes have been applied.
• Stopping distance = thinking distance + breaking distance.
• Factors that affect braking distance:

  • Speed
  • Road conditions
  • Tyre conditions
  • Brake conditions
• If the braking distance to stop a vehicle is very large, the brakes may overheat and the vehicle may skid.
• Conservation of momentum:

  In a closed system, the total momentum before an event is equal to the total momentum after it.
• Force acting on an object = rate of change of momentum