Work

• Work is done whenever a force moves.• The unit of work is the Joule (J)• 1 joule of work is done when a force of 1

newton moves a distance of l metre• 1 N 1 m

• There is an equation for calculating work:• Work done = force x distance moved

Work done = force x distance moved 1 joule = 1 newton x l metre

1 J = 1 x 1 Nm

To make the calculations easier we use a triangle W

F x d ÷ ÷

W = F x dCalculate the work done when a force of 2N moves an object 3M

Cover the quantityto be calculated with your fingerTo get the equation

W = F x d

W

F x d

The variables must be in their correct SI unitsWork = Joules (J)Force = Newton (N)Distance = Metres(M)

Work done (J) = Force (N) x Distance (m) ? (J) = 2 (N) x 3 (m) ? (J) = 2 x 3 (Nxm)

Given:Force = 2 NDistance = 3 mWork done = ? J

Substitute

W = F x dCalculate the work done when a force of 12N moves an object 0.5M

Cover the quantityto be calculated with your fingerTo get the equation

W = F x d

W

F x d

The variables must be in their correct SI unitsWork = Joules (J)Force = Newton (N)Distance = Metres(M)

Work done (J) = Force (N) x Distance (m) ? (J) = (N) x (m) ? (J) = (Nxm)

Given:Force = ? NDistance = ? mWork done = ? J

Substitute

W = F x dCalculate the work done when a force of 10 N moves an object 10mm

Cover the quantityto be calculated with your fingerTo get the equation

W = F x d

W

F x d

The variables must be in their correct SI unitsWork = Joules (J)Force = Newton (N)Distance = Metres(M)

Work done (J) = Force (N) x Distance (m) ? (J) = (N) x (m) ? (J) = (Nxm)

Given:Force = ? NDistance = ? mWork done = ? J

Substitute

W = F x dCalculate the force used when 24 J of work moved an object 6 m

Cover the quantityto be calculated with your fingerTo get the equation

F = W d F = W ÷ d

W

F x d

Force(N) = Work done (J) ÷ Distance (m)

Given:Force = ? NDistance = 6 mWork done = 24 J

Substitute

Remember 1 Joule = 1 Nm Nm cancel to N m

F = W = 24 d 6 = 4 N

W = F x dWhen a force of 6 N is applied and 42 J of work are done how far would the fly

travel across the room ?

Cover the quantityto be calculated with your fingerTo get the equation

d = W F d = W ÷ F

W

F x d

Force(N) = Work done (J) ÷ Distance (m)

Given:Force = 6 NDistance = ? mWork done = 42 J

Substitute

Remember 1 Joule = 1 Nm Nm cancel to m N

d = W = 42 F 6 = 7 m

More calculations:• How much work does a gardener do when he pushes a wheel barrow with a force of 75N for a distance of 20 metres?

• A boy climbs stairs 3m high and does 1800J of work. Calculate the force of the boy?

•A car brakes hard and its tyre marks stretch for 40m. A force of 400N was applied to cause the car to stop. How much energy was converted to heat and sound?

•How far would a 600N skateboarder travel if he has just eaten a 1450kJ hamburger for lunch?