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Work and energy As we know from the law of conservation of energy: energy is always conserved. Work is the product of force and the distance over which it moves. Imagine you are pushing a heavy box across the room. The further you move the more work you do! If W is work, F the force acting at an angle ? and s the distance then. W = FsCos? Energy comes in many shapes. The ones we see over here are kinetic energy (KE) and potential energy (PE) Transitional KE = ½ mv2 Rotational KE = ½ I2 here I is the moment of inertia of the object (a simple manner in which one can understand moment of inertia is to consider it to be similar to mass in transitional KE) Gravitational PE = mgh where h is the height of the object Elastic PE = ½k L 2 where k is the spring constant ( it gives how much a spring will stretch for a unit force) and L is the length of the spring. Simple isn't it!! |
Power
Power (P) is work( W) done in unit time (t).
P = W/t
as work and energy (E) are same it follows that power is also energy consumed or generated per unit time.
P = E/t
In measuring power Horsepower is a unit which is in common use. However in physics we use Watt. So the first thing to do in solving any problem related to power is to convert horsepower to Watts. 1 horsepower (hp) = 746 Watts
