WORK, ENERGY & POWER

Work  A measure of the amount of energy transformed from one form to another  For example, work is done when energy is used to move something or produce heat or light  Units: Joules (J)  A measure of the amount of energy transformed from one form to another  For example, work is done when energy is used to move something or produce heat or light  Units: Joules (J)

Energy  Energy is the ability to do work  Units: Joules (J)  Energy is the ability to do work  Units: Joules (J)

Potential Energy  Stored energy  Examples:  Gravitational  Elastic  chemical  Stored energy  Examples:  Gravitational  Elastic  chemical

Kinetic Energy  Energy of objects in motion  Heat and light are forms of kinetic energy  Energy of objects in motion  Heat and light are forms of kinetic energy

Electrical Energy  Electrical energy can be transformed into many other kinds of energy  Examples: heat, light, sound, mechanical energy  Electrical energy can be transformed into many other kinds of energy  Examples: heat, light, sound, mechanical energy

Power  The rate at which work is done  (more work in less time = more power)  Units: Watts (W) or kilowatts (kW)  The rate at which work is done  (more work in less time = more power)  Units: Watts (W) or kilowatts (kW)

Formulas  P = power (W)  E = Energy (J)  T = time (s)  V = volts (V)  I = current (A)

Sample Problems p P = P = = 686 W 1. P = P = = 686 W

2. E = Pt = 45 W x (28 x 60)s = J 2. E = Pt = 45 W x (28 x 60)s = J

4. P = VI = 0.42 V x 1.8 A = 0.76 W 4. P = VI = 0.42 V x 1.8 A = 0.76 W

5. V = = = 14.2 V 5. V = = = 14.2 V