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Work - Science lesson

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I use this powerpoint to teach work to my science students.

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Work - Science lesson

1. 1. Calculating Work <ul><li>To calculate work </li></ul><ul><li>Work = force x distance </li></ul><ul><li>W = F x d </li></ul>
2. 2. Example <ul><li>A teacher applies a force of 50N to move a students bag 10m. How much work is done? </li></ul><ul><li>W = Fxd </li></ul><ul><li>W = 50 x 10 </li></ul><ul><li>W = 500J </li></ul>
3. 3. Work (energy) <ul><li>The amount of energy being used is called WORK. </li></ul><ul><li>It is measured in units called joule, symbol J </li></ul><ul><li>Work = Force used x distance moved </li></ul><ul><li>(In joules) = (in newtons) (in metres) </li></ul>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
4. 4. 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?
5. 5. 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
6. 6. 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
7. 7. Problem 1 Work = Force x distance
8. 8. Problem 2
9. 9. Problem 3
10. 10. Problem 4
11. 11. Answers <ul><li>W = F x d </li></ul><ul><li>1 1750 x 2 = 3500 J </li></ul><ul><li>2 5000 x 10 = 50000J </li></ul><ul><li>3 1000 x 15 = 15000 J </li></ul><ul><li>4 10000 x 2 = 20000J </li></ul>