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Drills on Work, Energy and Power

Drills on Work, Energy and Power. 1. A motor does 5,000 joules of work in 20s. What is the power of the motor ? Given: W = 5,000 J, t = 20s Required: P = ? Sol’n : P = P = P = P = 250 P = 250 W.

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Drills on Work, Energy and Power

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  1. Drills on Work, Energy and Power

  2. 1. A motor does 5,000 joules of work in 20s. What is the power of the motor? Given: W = 5,000 J, t = 20s Required: P = ? Sol’n: P = P = P = P = 250 P = 250 W

  3. 2. A machine does 1,500 joules of work in 30s . What is the power of this machine? Given: W = 1,500 J, t = 30s Required: P = ? Sol’n: P = P = P = P = 50 P = 50 W

  4. 3. A toaster oven uses 67,500 joules of energy in 45 seconds to toast a piece of bread. What is the power of the oven? Given: W = 67,500 J, t = 45s Required: P = ? Sol’n: P = P = P = P = 1,500 P = 1,500 W

  5. 4. A horse moves a sleigh 1.00 kilometer by applying a horizontal 2,000-newton force on its harness for 2,500 seconds. What is the power of the horse? Given: F = 2,000 N, d = 1,000m, t = 2,500s Required: P = ? Sol’n: P = P = P = P = 800 P = 800 W

  6. 5. Suppose a force of 100 Newtons is used to push an object a distance of 5 meters in 15 seconds. Find the work done and the power for this situation. Given: F = 100 N, d = 5m, t = 15s Required: W = ?, P = ? Sol’n: W = Fd = (100N) (5m) = 500 J P = P = P = 33.33 W

  7. 6. Emily’s vacuum cleaner has a power rating of 200 watts. If the vacuum cleaner does 360,000 joules of work, how long did Emily spend vacuuming? Given: P = 200 W, W = 360,000 J Required: t = ? Sol’n: P = t = t = t = 1,800 s

  8. 7. A force of 100 newtons is used to move an object a distance of 15 meters with a power of 25 watts. Find the work done and the time it takes to do the work. Given: F = 100 N, d = 15m, P = 25 W Required: W = ?, t = ? Sol’n: W = Fd = 100 N (15m) = 1500 J t = t =

  9. 8. What is the power of cart having a mass of 25kg and has an acceleration of 30m/ in a period of 30s covering a distance of 100m? Given: m = 2,500kg, a = 30m/, t = 30s, d= 100m Required: P = ? Sol’n: F = ma = 25kg (30m/) = 750 N W = Fd = 750 N (100m) = 75,000 J P = =

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