Ms. Westendorf's Physical Science - Home



Work and Power PracticeDirections: ?Answer the following questions on separate sheet of paper.1. ?Define work.Requires a force acting on an object in the same direction that it is moving.2. ?What is the equation for work?W = F x d3. ?Define power.Power is a rate. It is the amount of work done in a given amount of time.4. ?What is the equation for power?P = worktimeTRUE/FALSE5. ?Power depends on how fast you do the work. True6. ?Power is measured in Newtons. False -- Watts7. ?Carrying an object is doing work. False -- lifting8. ?Work is a form of energy. TrueDirections: ?Determine whether work is done in the following situations.9. ?You carry groceries inside your house.No work10. ?You give your sister a piggy back ride.No work11. ?You lift up box onto a table.Work12. ?You walk to school.No workDirections: ?Solve the following problems using the work and power equation. ?You must show your work and include the correct units.13. ?You must exert a force of 4.5 N on a book to slide it across the table. ?If you do 2.7 J of work in the process, how far have you moved the book?W = F x dW = 2.7 JF = 4.5 Nd = ? m2.7 J = 4.5 N x dd = 0.6 m14. ?A child pulls a sled up a snow covered hill. ?The child does 405 J of work on the sled. ?If the child walks 15 m up the hill, how large of a force must the child exert?W = F x dW = 405 JF = ? Nd = 15 m405 J = F x 15 mF = 27 N15. ?How much work is done on a small car if a 3150 N force is exerted to move it 75.5 m to the side of the road?W = F x DW = ? JF = 3150 Nd = 75.5 mW = 3150 N x 75.5 mW = 237,825 J16. ?A 190,000 W engine can accelerate from rest to a top speed in 9 s. ?How much work did the engine do?P = worktimeP = 190,000 WW = ? Jt = 9 s190,000 W = W9 sW = 1,710,000 J17. ?Another engine reaches its top speed from rest in 7.5 seconds. ?It is able to perform 250,000 J of work in that time. ?How much power does this engine have in that time?P = worktimeP = ? WW = 250,000 Jt = 7.5 sP =250,000 J7.5 sP = 33,333 W18. ?If a runner exerts 350 J of work to make 125 W of power, then how long did it take the runner to do the work?P = worktimeP = 125 WW = 350 Jt = ? s125 W = 350 Jtimet = 2.8 s ................
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