TOPIC 6: Potential Energy and Conservation of Energy
Gravitational Potential Energy and Escape Velocity
Conservative and Nonconservative Forces
Conservative -the work done by the force on an object depends only on the initial and final positions of the object, and is independent of the particular path taken.
Nonconservative-A non-conservative force is one for which work depends on the path taken
Potential Energy
Potential energy is energy that is stored or conserved in an object or substance.
-based on the position, arrangement or state of the object or substance.
Gravitational PE ~ U=mgh
Elastic PE ~ U=1/2 kx^2
Mechanical Energy and Its Conservation
If there are no nonconservative forces, the sum of the changes in the kinetic energy and in the potential energy is zero
Total mechanical energy= U + K
principle of conservation of mechanical energy
If only conservative forces are doing work, the total mechanical energy of a system stays constant and conserved.
The Law of Conservation of Energy
Energy can be transferred, but cannot created or destroyed
Total energy still conserved if non-conservative force are taken into account
△U + △K + △[other energy] = 0
Escape velocity is minimum velocity needed by anybody or object to be projected to overcome the gravitational pull of the planet earth
Power
rate at which work is done
Average power
-work done divided by the time it takes to do work
Instantaneous power
-dW/dt = Fv
CHAI YING YING
A20SC0035