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Eagle Project Physics Phun Part 3

Justin Gallagher

Entry posted by Justin Gallagher

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If you have seen part 2, you will know that this time we are going to be looking into sledgehammers. For my project, I required the use of a sledgehammer to pound 1 meter re-bar into the ground, 14 times. The reason I am using re-bar in this project is to allow the walk path to stay in the same position, while the ground shifts overtime. The average distance the re-bar traveled was .05 m, therefor requiring 20 swings, which each had an average force of about 100 N, exerted over an interval of .02 seconds.

From this information, we can find the power of each strike and in total for all 14 bars. Power is equal to the change in Work over the Change in time. So, if we use the force and the displacement, we find that the change in work is 5 Joules. If we put this into our equation for power, we get 250 Watts per swing. From this we can determine that if it takes 20 swings per rod, and there are 14 rods, it requires a total amount of 70000 watts of power.

If I used a heavier sledgehammer, I would be able to exert more force over the same time interval, thus displacing the re-bar farther into the ground. However, this would come at the price of exerting more force to keep the hammer up, tiring me out faster.

Here are pictures of my fellow scouts helping hammer in the re-bar.

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blogentry-2754-0-70911500-1414975549_thu

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