Here’s the step-by-step solution to each problem on the “Works, Power, and Energy” worksheet.
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1. How much power does it take to lift 30.0 N 10.0 m high in 5.00 s?
-
Work (W) = Force × Distance
→ W = 30.0 N × 10.0 m =
300 J
-
Power (P) = Work ÷ Time
→ P = 300 J ÷ 5.00 s =
60.0 W
✔ Answer: 60.0 Watts
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2. How much power does it take to lift 30.0 kg 10.0 m high in 5.00 s?
- First, convert mass to force (weight):
Force (F) = mass × gravity = 30.0 kg × 9.8 m/s² =
294 N
- Work (W) = F × d = 294 N × 10.0 m =
2940 J
- Power (P) = W ÷ t = 2940 J ÷ 5.00 s =
588 W
✔ Answer: 588 Watts
*(Note: Some curricula use g = 10 m/s² for simplicity — if so, answer would be 600 W. But standard physics uses 9.8 m/s².)*
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3. You move a 25 N object 5.0 meters. How much work did you do?
- Work (W) = Force × Distance
→ W = 25 N × 5.0 m =
125 J
✔ Answer: 125 Joules
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4. You carry a 20. N bag of dog food up a 6.0 m flight of stairs. How much work was done?
- Work is done against gravity: W = Force × Distance (vertical)
→ W = 20. N × 6.0 m =
120 J
✔ Answer: 120 Joules
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5. You push down on a 3.0 N box for 10. minutes. How much work was done?
- Work = Force × Distance × cosθ
But here, you’re pushing
down — if the box doesn’t move vertically or horizontally,
distance = 0.
→ W = 3.0 N × 0 m =
0 J
*(Even though you’re applying force, no displacement means no work is done in physics terms.)*
✔ Answer: 0 Joules
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6. You use 35 J of energy to move a 7.0 N object. How far did you move it?
- Work = Force × Distance → Distance = Work ÷ Force
→ d = 35 J ÷ 7.0 N =
5.0 m
✔ Answer: 5.0 meters
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7. You do 45 J of work in 3.0 seconds. How much power do you use?
- Power = Work ÷ Time
→ P = 45 J ÷ 3.0 s =
15 W
✔ Answer: 15 Watts
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8. A car uses 2,500 Joules in 25 seconds. Find power.
- Power = Work ÷ Time
→ P = 2500 J ÷ 25 s =
100 W
✔ Answer: 100 Watts
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📌 Summary of Answers:
1.
60.0 W
2.
588 W *(or 600 W if using g=10 m/s²)*
3.
125 J
4.
120 J
5.
0 J
6.
5.0 m
7.
15 W
8.
100 W
Let me know if you’d like these explained with diagrams or formulas!
Parent Tip: Review the logic above to help your child master the concept of work and energy worksheet.
