# What is considered a small velocity?

1. Oct 7, 2012

### Fellowroot

1. The problem statement, all variables and given/known data

An elevator is being pulled upwards with an small inital velocity. The elevator cable has a constant tension. After 250 seconds it stops with a gravitational energy of 2400J. Assume the acceleration due to gravity is 10. What is the mass of the elevator?

2. Relevant equations

PE=mgh

3. The attempt at a solution

Assume what v is then see how high it is then plug in to find m.
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Anyway, when a problem says that something is traveling at a small velocity, but does not state what velocity to use, what should we take it as.

This is actually what I don't like about physics. In math if I am given an integral to solve I don't assume anything, I just do it.

I remember in thermodynamics, there was this one problem about a turbine and I tried very very hard to solve it without looking at the solutions manual. Then finally I gave up and looked at the manual and guess what. There was like 3 different assumptions you had to make an order to solve it. Thanks a lot physics.

2. Oct 7, 2012

### _h2tm

Maybe try looking up the average speed of an elevator and take half of that ... or just go with .01 m/s.