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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:
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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 metre1 J = 1 x 1 Nm W F x d To make the calculations easier we use a triangle ÷ ÷
W = F x dCalculate the work done when a force of 2N moves an object 3M Given: Force = 2 N Distance = 3 m Work done = ? J Substitute Cover the quantity to be calculated with your finger To get the equation W = F x d W F x d Work done (J) = Force (N) x Distance (m) ? (J) = 2 (N) x 3 (m) ? (J) = 2 x 3 (Nxm) The variables must be in their correct SI units Work = Joules (J) Force = Newton (N) Distance = Metres(M)
W = F x dCalculate the work done when a force of 12N moves an object 0.5M Given: Force = ? N Distance = ? m Work done = ? J Substitute Cover the quantity to be calculated with your finger To get the equation W = F x d W F x d Work done (J) = Force (N) x Distance (m) ? (J) = (N) x (m) ? (J) = (Nxm) The variables must be in their correct SI units Work = Joules (J) Force = Newton (N) Distance = Metres(M)
W = F x dCalculate the work done when a force of 10 N moves an object 10mm Given: Force = ? N Distance = ? m Work done = ? J Substitute Cover the quantity to be calculated with your finger To get the equation W = F x d W F x d Work done (J) = Force (N) x Distance (m) ? (J) = (N) x (m) ? (J) = (Nxm) The variables must be in their correct SI units Work = Joules (J) Force = Newton (N) Distance = Metres(M)
W = F x dCalculate the force used when 24 J of work moved an object 6 m Given: Force = ? N Distance = 6 m Work done = 24 J Substitute Cover the quantity to be calculated with your finger To get the equation F = W d F = W ÷ d W F x d Force(N) = Work done (J) ÷ Distance (m) F = W = 24 d 6 = 4 N Remember 1 Joule = 1 Nm Nm cancel to N m
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 ? Given: Force = 6 N Distance = ? m Work done = 42 J Substitute Cover the quantity to be calculated with your finger To get the equation d = W F d = W ÷ F W F x d Force(N) = Work done (J) ÷ Distance (m) d = W = 42 F 6 = 7 m Remember 1 Joule = 1 Nm Nm cancel to m N
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?