- #1

PhyIsOhSoHard

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I have a problem understanding whether a sign should be positive or negative when it comes to a spring.

In my book, there is an example with a glider attached to a spring, and the glider is moving away from the spring so it expands.

It says that in order to use the work-energy theorem, it has to be the work done by the spring on the glider, which is the negative of the following equation:

[itex]W=\frac{1}{2}mv_2^2-\frac{1}{2}mv_1^2[/itex]

Can somebody explain the "work done by the spring" and "work done on the spring"? How do I know which situation I have?

Why is the work negative in this situation?

And if the glider went the opposite direction, towards the spring, would that mean the work-energy theorem is positive?

In my book, there is an example with a glider attached to a spring, and the glider is moving away from the spring so it expands.

It says that in order to use the work-energy theorem, it has to be the work done by the spring on the glider, which is the negative of the following equation:

[itex]W=\frac{1}{2}mv_2^2-\frac{1}{2}mv_1^2[/itex]

Can somebody explain the "work done by the spring" and "work done on the spring"? How do I know which situation I have?

Why is the work negative in this situation?

And if the glider went the opposite direction, towards the spring, would that mean the work-energy theorem is positive?

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