Let's solve each problem step by step using the mechanical advantage (MA) formula:
Mechanical Advantage Formula:
$$
\text{MA} = \frac{\text{Resistance Force (R)}}{\text{Effort Force (E)}}
$$
Alternatively, for levers when distances are given:
$$
\text{MA} = \frac{\text{Distance to Effort}}{\text{Distance to Resistance}}
$$
---
1. Screwdriver Problem
- Effort Force (E) = 30 N
- Resistance Force (R) = 90 N
$$
\text{MA} = \frac{90}{30} = 3
$$
✔ Answer: MA = 3
---
2. Lever Lifting Rock
- Mass of rock = 800 N → This is the
resistance force (R)
- Effort Force (E) = 200 N
$$
\text{MA} = \frac{800}{200} = 4
$$
✔ Answer: MA = 4
---
3. Bottle Opener
- Effort Force (E) = 55 N
- Resistance Force (R) = 675 N
$$
\text{MA} = \frac{675}{55} \approx 12.27
$$
(We can leave it as a decimal or fraction.)
✔ Answer: MA ≈ 12.27
---
4. Pulley System
- Effort Force (E) = 250 N
- Resistance Force (R) = 1250 N (mass of box in newtons)
$$
\text{MA} = \frac{1250}{250} = 5
$$
✔ Answer: MA = 5
---
5. Nutcracker – Given MA, Find Output Force
- Effort Force (E) = 75 N
- MA = 5
- We need to find the
Resistance Force (R)
Use:
$$
\text{MA} = \frac{R}{E} \Rightarrow R = \text{MA} \times E = 5 \times 75 = 375 \text{ N}
$$
✔ Answer: Force = 375 N
---
6. Lever with MA = 6, Output Force = 1800 N
- MA = 6
- Resistance Force (R) = 1800 N
- Find Effort Force (E)
$$
\text{MA} = \frac{R}{E} \Rightarrow E = \frac{R}{\text{MA}} = \frac{1800}{6} = 300 \text{ N}
$$
✔ Answer: Force = 300 N
---
7. Lever with Distances
From diagram:
- Distance from fulcrum to effort = 9 m
- Distance from fulcrum to resistance = 3 m
$$
\text{MA} = \frac{\text{Distance to Effort}}{\text{Distance to Resistance}} = \frac{9}{3} = 3
$$
✔ Answer: MA = 3
---
8. Lever with Distances
From diagram:
- Distance from fulcrum to resistance = 5 m
- Distance from fulcrum to effort = 20 m (total length), but wait — let's interpret carefully.
The object is placed
5 m from the fulcrum, and the effort is applied at the end of a
20 m lever. So:
- Distance to resistance = 5 m
- Distance to effort = 20 m
$$
\text{MA} = \frac{20}{5} = 4
$$
✔ Answer: MA = 4
---
✔ Final Answers:
1.
MA = 3
2.
MA = 4
3.
MA ≈ 12.27
4.
MA = 5
5.
Force = 375 N
6.
Force = 300 N
7.
MA = 3
8.
MA = 4
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Parent Tip: Review the logic above to help your child master the concept of simple machines mechanical advantage worksheet.