a) Work done

a) work done by a force; the unit joule

b) W = Fxcosθ for work done by a force

e) transfer of energy is equal to work done

c) the principle of conservation of energy

d) energy in different forms; transfer and conservation

work done = when energy is transferred

work done = when a force applied to an object moves the object in the line of action of the force

W = Fx

• work done on an object (J) = force applied to the object (N) × distance the object moved in the line of action of the force (m)

when a force is applied to an object at an angle to the direction of the object’s motion

W = Fcosθx

• work done on an object (J) = force applied to the object in the direction of the object’s motion (N) × distance the object moved (m)

principle of the conservation of energy

• total energy of a closed system remains constant

• energy cannot be created or destroyed, only transferred from one store to another