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### Work & Power Homework

- Determine the power dissipated when 800 J of work is done in 5 min. Ans: 2.67 W
- A box weighing 400 N is pulled up a 40 m incline to a point 1.6 m above its starting level. The force needed to pull the box is 20 N. Find the work output, the work input, the work to overcome friction, and the efficiency of the machine. Ans: 640 J; 800 J; 160 J; 0.80
- By applying a force of 75 N over a distance of 8 m to a set of pulleys, a student raises a 300 N object to a height of 1.5 m above the floor. What is the work input, the work output, the work to overcome friction, and the efficiency of the pulleys as a machine? Ans: 600 J; 450 J; 150 J; 0.75
- For the set of pulleys in number 3, determine the MA and the IMA. Ans: 4.00; 5.33
- A certain machine does 5000 J of useful work and expends 1000 J in overcoming friction. Find the work input and the efficiency. Ans: 6000 J; 0.83
- A 600 N box is raised 6 m by a machine that has an efficiency of 0.60. What is the work input, work output, and the work done to overcome friction? Ans: 6000 J; 3600 J; 2400 J
- A 200 N force is used to pull a box a distance of 10 m along a floor by a rope attached at a 40° angle to the box. What work is done to pull the rope? Ans: 1532.09 J
- A 400 N force is used to push a carton weighing 1000 N a distance of 5 m across the floor. The force is applied to the carton at a 20° angle. What work is done? Ans: 1879.39 J

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