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Hello everyone.
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In this problem, we have to find changing the potential energy for wrecking pole as it is erased through or like pulled back through an angle of 25 degrees while it is hung on a cable of 15 meters.
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We're told that the mass of the vol is a thousand kilograms and we know that the gravitational acceleration is 9 .8 meters per second squared.
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And so what we have to find is the change in potential energy, which given that we set up the the problem such that the lowest position of the wrecking ball is at zero meters.
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So that's going to be a reference value.
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We can just call the height in elevation h.
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And so with that, change in potential linear is going to be mass of the ball times g times h.
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Now the tricky part here is finding what h is.
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So if you look at this triangle that i've drawn here in the figure, then essentially what you have is this.
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You have two sides of the triangle being equal to l, and then there is some unknown side, but it's also true that there's going to be a 90 degree angle between these two triangles over here.
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So why is that useful? well, that's useful because we can calculate and we can split this right part or right side of the triangle into two parts.
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One we can call x, and the other one we can call h.
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And so we know, that l is going to be h plus x.
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And so why is that useful? why is useful? because we can use the fact that this is the right -hand of the triangle on the top to find what x is.
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So we know that if we just had this triangle, where you have l on one side, there is something on the bottom...