Ms. Westendorf's Physical Science - Home



WORK AND POWER #2Solve the following problems. Show all your work. Remember to include the correct units. COMPLETE THIS ON A SEPARATE SHEET OF PAPER!1. How much work is done by a crane that lowers 1000 newtons of material a distance of 150 meters??W = F x dW = ? JF = 1000 Nd = 150 mW = 1000 N x 150 mW = 150,000 J2. ?How much work is done when a 1-kilogram mass is raised a vertical distance of 1 meter?w = mgw = 1 kg x 9.8 m/s2W = F x d?F = 9.8 Nd = 1 mW = 9.8 N x 1 mW = 9.8 J3. ?A 5-kilogram rock is lifted 2 meters in 5 seconds.a. How much work is done?w = mgw = 5 kg x 9.8 m/s2w = 49 N W = F x dW = ? JF = 49 Nd = 2 mW = 49 N x 2 mW = 98 Jb. ?What power is used?P = worktimeP = ? WW = 98 Jt = 5 sP = 98 N5 sP = 19.6 W4. ?A teacher pushed a desk across a floor for a distance of 5 meters. She exerted a horizontal force of 20 newtons. How much work was done??W = F x dW = ? JF = 20 Nd = 5 mW = 20 N x 5 mW = 100 J5. ?A weight lifter lifts a 150-kg barbell above his head from the floor to a height of 2m. He holds the barbell there for 5 sec. How much work does he do during that 5-sec interval?During the 5 second interval there is no movement from the weight lifter. If there is no movement there is no work being done.6. ?A student who weighs 500 newtons climbed the stairs form the first floor to the third floor, 15 meters above, in 20 seconds.a. How much work did she do?W = F x dW = ? JF = 500 Nd = 15 mW = 500 N x 15 mW = 7,500 Jb. ?What is her power? P = worktimeP = ? WW = 7,500 Jt = 20 sP = 7,500 J20 sP = 375 W7. ?A box is pushed across the floor for a distance of 5 meters with a force of 50 newtons in 5 seconds.a. How much work is done?W = F x d W = ? JF = 50 Nd = 5 mW = 50 N x 5 mW = 250 Jb. ?What is her power?P = worktimeW = 250 Jt = 5 sP = 250 J5 sP = 50 W8. ?A woman lifts a 35-kg child a distance of 1.5 meters and carries her forward for 6.5 m.a. How much work does the woman do in lifting the child??w = mgw = 35 kg x 9.8 m/s2w = 343 NW = F x dF = 343 Nd = 1.5 mW = 343 N x 1.5 mW = 514.5 Jb. ?How much work does the child do?The child does not do any work. The child is pushing down with a 343 N force while moving upward. The force and the distance are not acting in the same direction.?9. ?If 4000 Joules are used to raise a 30-kilgrams mass, how high is the mass raised??w = mgw = 30 kg x 9.8 m/s2w = 294 NW = F x dW = 4,000 JF = 294 Nd = ? m4,000 J = 294 N x dd = 13.6 m10. ?A force used to lift a 12-kilogram mass to a height of 8 meters in 2 seconds does 1040 joules of work.a. How much force is used?W = 1040 JF = ? Nd = 8 m1040 J = F x 8 mF = 130 Nb. What power is developed?P = WorktimeW = 1040 Jt = 2 sP = 1040 J2 sP = 520 W ................
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