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I use this powerpoint to teach work to my science students.
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Calculating WorkCalculating Work
To calculate workTo calculate work
Work = force x distanceWork = force x distance
W = F x dW = F x d
ExampleExample
A teacher applies a force of 50N to A teacher applies a force of 50N to move a students bag 10m. How move a students bag 10m. How much work is done?much work is done?
W = FxdW = Fxd
W = 50 x 10W = 50 x 10
W = 500JW = 500J
Work (energy)Work (energy)
The amount of energy being used is called The amount of energy being used is called WORK.WORK.
It is measured in units called joule, symbol JIt is measured in units called joule, symbol J
Work = Force used x distance movedWork = Force used x distance moved (In joules) = (in newtons) (in metres)(In joules) = (in newtons) (in metres)
Aim - to find out how much work it is to lift weights
Example - Steve bench presses 100Kg a distance of 0.5m
How much work has he done
100Kg = a weight force of 1000N so …..
Work = 1000 x 0.5= 500 joules
Now try the problems below.
1 Kevin lifts 150 kg in a clean and jerk, a distance of 2m. How much work has he done?
2 Stephanie curls 40kg a distance of 0.2 m. How much work has she done?
3 Steven military presses 80Kg a distance of 0.5m. He does this five times. How much work has he done?
4 Rob side lifts a 15Kg dumbbell 0.3m. He does this 30 times. How much work has he done?
1 Kevin lifts 150 kg in a clean and jerk, a distance of 2m. How much work has he done?
Weight = 150Kg x 10N/Kg = 1500N
Work = Force x distance
= 1500N x 2m
= 3000 Joules = 3 kJ
2 Stephanie curls 40kg a distance of 0.2 m. How much work has she done?
Weight = 40Kg x 10N/Kg = 400N
Work = Force x distance
= 400N x 0.2m
= 80 Joules
3 Steven military presses 80Kg a distance of 0.5m. He does this five times. How much work has he done?
Weight = 80Kg x 10N/Kg = 800N
Work = Force x distance
= 800N x 0.5m
= 400 Joules x 5 = 2,000 joules = 2 kJ
4 Rob side lifts a 15Kg dumbbell 0.3m. He does this 30 times. How much work has he done?
Weight = 15Kg x 10N/Kg = 150N
Work = Force x distance
= 150N x 0.3m
= 45 Joules x 30 times = 1,350 Joules = 1.35 kJ
Problem 1Problem 1
Work = Force x distance
Problem 2Problem 2
Problem 3Problem 3
Problem 4Problem 4
AnswersAnswers
W = F x dW = F x d
11 1750 x 2 = 3500 J1750 x 2 = 3500 J
22 5000 x 10 = 50000J5000 x 10 = 50000J
33 1000 x 15 = 15000 J1000 x 15 = 15000 J
44 10000 x 2 = 20000J10000 x 2 = 20000J
