Force and Motion

• The greater the resultant force on an object, the greater the object's acceleration.
• The greater the mass of an object, the smaller its acceleration for a given force.
• The inertia of an objects is its tendency to stay at rest or in uniform motion.
• The weight of an object is the force acting on the object due to gravity. Its mass in the quantity of matter in the object.
• The ternminal velocity of an object is the velocity it eventually reaches when it is falling. The weight of the object is then equal to the frictional force on the object.
• When an object is moving at terminal velocity, the resultant force on it is zero.
• Friction and air resistance oppose the driving force of a vehicle.
• The stopping distance of a vehicle depends on the thinking distance and the braking distance.
• High speed, poor weather conditions and poor vehicle maintenance all increase the braking distance.
• Poor reaction time due to tiredness, alcohol, drugs, or using a mobile phone and high speed increases the thinking distance.
• Force = Mass x Acceleration gives the braking force of a vehicle
• The deceleration of a vehicle can be calculated using the equation v^2=u^2+2as
• The momentum of a moving object is:

  Momentum = Mass x Velocity
• The unit of momentum is kgm/s
• A closed system is a sytem in which the total momentum before an event is the same as the total momentum after the event. This is called conservation of momentum.
• An object is called elastic if it returns to its original shape after removing the force deforming it.
• The extension is the difference between the length of the object and its original length.
• The extension of a spring is directly proportional to the force applied to it, as long as the limit of proportionality is not exceeded. This relationship is linear.
• Beyond the limit of proportionality, the extension of a spring is no longer proportional to the applied force. This relationship becomes non-linear.