Work - Science lesson
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The document discusses the concept of work in physics and provides examples of calculating work done by lifting weights. It defines work as the product of the applied force and distance of movement. Several word problems are given as examples, asking the reader to calculate work done by individuals lifting various weights different distances and numbers of times. Formulas and step-by-step workings are shown for calculating work from given values of force, distance, and number of lifts.
Work - Science lesson
- 1. Calculating Work To calculate work Work = force x distance W = F x d
- 2. Example A teacher applies a force of 50N to move a students bag 10m. How much work is done? W = Fxd W = 50 x 10 W = 500J
- 3. Work (energy) The amount of energy being used is called WORK. It is measured in units called joule, symbol J Work = Force used x distance moved (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
- 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. 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. 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. Problem 1 Work = Force x distance
- 8. Problem 2
- 9. Problem 3
- 10. Problem 4
- 11. Answers W = F x d 1 1750 x 2 = 3500 J 2 5000 x 10 = 50000J 3 1000 x 15 = 15000 J 4 10000 x 2 = 20000J