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Hello everyone,

I was wondering if anyone could shed some light on the following problem:

While composing a practise test for a chapter about conservation of energy, I made a problem like the one in the image, but because I was too fast I used physically impossible values: radius = 2.0 m, α = 60° and the friction force equals 10 N. This obviously meant that v^2 gave a negative value.

However that's a problem easily solved by fixing the values. The problem I came across is that I got a different solution than someone else, while the only difference in our calculations was where we put the y = 0 line.

I considered the bottom B of the circle to be y = 0, which means that you get potential energy on the left and the right side of the balance.

The other person put the y = 0 at the horizontal line through C which means that he only gets mgΔy at the left side.

Has anyone got a clue as to why we get different values?

Thanks in advance,

Tom Koolen

Hello everyone,

I was wondering if anyone could shed some light on the following problem:

While composing a practise test for a chapter about conservation of energy, I made a problem like the one in the image, but because I was too fast I used physically impossible values: radius = 2.0 m, α = 60° and the friction force equals 10 N. This obviously meant that v^2 gave a negative value.

However that's a problem easily solved by fixing the values. The problem I came across is that I got a different solution than someone else, while the only difference in our calculations was where we put the y = 0 line.

I considered the bottom B of the circle to be y = 0, which means that you get potential energy on the left and the right side of the balance.

The other person put the y = 0 at the horizontal line through C which means that he only gets mgΔy at the left side.

Has anyone got a clue as to why we get different values?

Thanks in advance,

Tom Koolen

## Homework Statement

## Homework Equations

## The Attempt at a Solution

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