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Name: ____________________
Work/Simple Machines Practice Problems
FORMULAS:
Work = Force multiplied by Distance
Power = Work divided by Time or
Power = Force X Distance divided by Time
Mech. Eff. = Output divided by Input X 100
What’s the unit?
1. Work? __________
2. Power? __________
3. Mechanical Efficiency? _________
SOLVE- Solve each problem using correct units.
Find Work.
1. Force = 50N Distance = 3 m
Work = _____________________
2. Force = 4 N Distance = 7 m
Work = _____________________
3. Force = 40N Distance = 4 m
Work = _____________________
4. Force = 35 N Distance = 2 m
Work = _____________________
5. Force = 30 N Distance = 5 m
Work = _____________________
Find Power.
1. Work = 80 J Time = 10 s
Power = _________________
2. Work = 120 J Time = 3 s
Power = _________________
3. Work = 240 J Time = 6 s
Power = _________________
4. Work = 500 J Time = 5 s
Power = _________________
5. Force = 40 N Distance = 3 m Time = 4s
Power = ____________________
6. Force = 10 N Distance = 10 m Time = 5 s
Power = ____________________
Find Mechanical Efficiency.
1. Work Output = 50 J Work Input = 100 J
ME = _______________________
2. Work Output = 20 J Work Input = 80 J
ME = ________________________
3. Work Output = 18 J Work Input = 25 J
ME = ________________________
4. Work Output = 18 J Work Input = 30 J
ME = ________________________
Word Problems- Solve each.
1. A football player with the force of 500 N leaps 2 m into the air. How much work was done?
2. A weightlifter raises a 700 N barbell a distance of 3 m. How much work was done?
3. What is the power of a blender that uses 1000 J in 5 s?
4. What is the power of a light bulb that uses 480 J in 8 s?
5. How much power is used if a force of 35 N is used to push a box a distance of 10 m in 5 s?
6. A box is moved up an inclined plane using 100 J of energy. The amount of work produced is 80 J. What is the mechanical efficiency?
7. A person put 50 J of energy into using a pulley to get 45J of work done. What is the mechanical efficiency?
