- #1

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I am having trouble solving this and I was wondering if someone could give me a hint?

I currently have reached a dead end with:

2 delta r

-------- = %SA

r

However, I don't have any known r values to work with...

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- Thread starter Procrastinate
- Start date

- #1

- 158

- 0

I am having trouble solving this and I was wondering if someone could give me a hint?

I currently have reached a dead end with:

2 delta r

-------- = %SA

r

However, I don't have any known r values to work with...

- #2

Cyosis

Homework Helper

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- #3

Mark44

Mentor

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You will also need differentials dr, dS, and dV, since you want dS/S. Recall that dS = dS/dr * dr.

- #4

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My final answer was 2.4%; was that right?

- #5

HallsofIvy

Science Advisor

Homework Helper

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There is an engineer's rule of thumb, derived from the differential of Mark44, that "if measurements add, their errors add, if measurements multiply, their **percentage** errors add. Since here, you have a percentage error of .008 in r, and [itex]V= (4/3)\pi r^3[/itex] involves multiplying r three times, yes, the percentage error in V is 3(.008)= 0.024 or 2.4%.

Last edited by a moderator:

- #6

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Procrastinate, try finding the % error in

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