# Homework Help: Oscillation speed question

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1. Nov 28, 2015

### Jordan&physics

Mentor Note -- thread moved from the technical forums, so no HH Tempate is shown...>>
1. (10 points) A pendulum of length l = 39 cm is suspended in a railway car. At what train speed would the pendulum be oscillating with largest amplitude ? The length of the rails is l = 25 m.

I am just not sure what the question is asking :-/ Why would the pendulum oscillate if the train was moving at a constant velocity? It doesn't specify an acceleration, and I don't know what they mean by specifying the "length of rails." Please, I am really lost on this one.

Last edited by a moderator: Nov 28, 2015
2. Nov 28, 2015

### Staff: Mentor

Yeah, based on what you posted, this question makes no sense IMO. Can you scan the problem so we can see if there is additional info?

3. Nov 28, 2015

### Jordan&physics

I actually copied and pasted it directly from the problem set. There was absolutely no more information given.

4. Nov 28, 2015

### Staff: Mentor

Yikes, can you e-mail a TA or prof for clarification?

5. Nov 28, 2015

### Staff: Mentor

Could this be a model train, flying round and round on a circular track, circumference 25m?

6. Nov 28, 2015

### Staff: Mentor

Could be that the finite rail lengths are intended to be responsible for a "clickety-clack" that slightly jounces the train carriage at regular intervals. A tuned system like a pendulum would be sensitive to particular frequencies...

7. Nov 29, 2015