ZIMSEC O Level Combined Science Notes: Experiment:Finding the mechanical advantage of an inclined plane

Aim: Finding the Mechanical Advantage of an inclined plane

Materials: 1m long plank, sandpaper, bricks. cotton reel, nails, thick steel wire, wood block (smoothed on the underside) weights/tin and sand, pliers, string, spring balance/scales Finding the mechanical of an inclined plane

Method

1. Use sand paper to smooth the underside of the wooden block
2. Prop up the 1m plank piece using bricks and put a pulley on the top end as shown above
3. Weigh the wooden block
4. Measure the length of the plank
5. Attach a piece of string to the brick using a nail and loop it through the pulley as shown above
6. Place the wooden block at the bottom of the inclined plane and add weights or sand and attach it to the other end of the string and until the wood starts moving upwards
7. Measure the force (F) required
8. Measure the height (h) of the inclined plane
9. Place another brick in the pile and  to the pile and record the new distance h and force F
10. Record the results in a table
11. Using the weight of the wooden block as calculate the Mechanical Advantage of the plane each time

Results and Observations

• The mechanical advantage of the  of the inclined plane decreases when the inclined plane becomes steeper
• This means that a greater effort is required to move the load when the angle of the plane is steep (bigger)
• Conversely the Mechanical Advantage of the inclined plane increases as the slope (angle) of the plane becomes smaller
• The Velocity Ratio of the plane decreases when the inclined plane becomes steeper
• The Velocity Ratio of the plane increases when the inclined plane’s angle is made smaller

Conclusion

• Less effort is required to lift the load if the inclined plane’s angle becomes smaller
• However the load has to move a greater distance
• Work done by load can be calculated using the formula:
• Word done by load= W x d
• Word done by effort can be calculated using the formula:
• Word done by effort= F x h
• In theory the work done by load and effort should be equal
• This would mean the machine was 100% efficient
• In reality no machine is 100% efficient due to friction
• The efficiency of a machine can be calculated using the formula:
• $\text{Efficiency = }( \dfrac{ \text{W x d}}{\text{F x h}}) \text{x 100}$
• The result is given as a percentage

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