P2.2 The Kinetic Energy Of Objects Speeding Up Or Slowing Down

P2.2 The Kinetic Energy Of Objects Speeding Up Or Slowing Down

1. P2.2.1 Forces And Energy

   • When a force causes an object to move through a distance work is done and energy is transferred.
     • W=F×d where W is the work done in joules, J, F is the force applied in newtons, N and d is the distance moved in the direction of the force in metres, m.
       • P=E/t where P is the power in watts, W. E is the energy transferred in joules, J and t is the time taken in seconds, s.
         • Ep=m×g×h where Ep is the change in gravitational potential energy in joules, J, m is the mass in kilograms, kg. g is the gravitational field strength in newtons per kilogram, N/kg and h is the change in height in metres, m
           • Ek=1/2×m×v2 where Ek is the kinetic energy in joules, J, m is the mass in kilograms, kg and v is the speed in metres per second, m/s.

2. P2.2.2 Momentum

   • Momentum is a property of moving objects: p=m×v where p is momentum in kilograms metres per second, kg m/s, m is the mass in kilograms, kg and v is the velocity in metres per second, m/s.
     • In a closed system the total momentum before an event is equal to the total momentum after the event. This is called conservation of momentum.