## Chapter Topics:

Work
Energy conversion and conservation
Efficiency
Potential energy and kinetic energy
Power

## Learning Objectives:

(a) Define and use work done by a force as the product of the force and displacement in the direction of the force.

(b) Calculate the work done in a number of situations including the work done by a gas which is expanding against a constant external pressure: W = p∆V

(c) Give examples of energy in different forms, its conversion and conservation, and apply the principle of energy conservation.

(d) Show an appreciation for the implications of energy losses in practical devices and use the concept of efficiency to solve problems.

(e) Derive, from the equations for uniformly accelerated motion in a straight line, the equation Eₖ = ½mv².

(f) Recall and use the equation Eₖ = ½mv².

(g) Distinguish between gravitational potential energy, electric potential energy and elastic potential energy.

(h) Deduce that the elastic potential energy in a deformed material is related to the area under the force-extension graph.

(i) Show an understanding of and use the relationship between force and potential energy in a uniform field to solve problems.

(j) Derive, from the definition of work done by a force, the equation Eₚ = mgh for gravitational potential energy changes near the Earth’s surface.

(k) Recall and use the equation Eₚ = mgh for gravitational potential energy changes near the Earth’s surface.

(l) Define power as work done per unit time and derive power as the product of a force and velocity in the direction of the force.