Homework Help: Physics lab

1. Oct 26, 2004

chathamchick

Okay...i did this lab where two different masses are on opposite ends of a string and hung over a pulley...how do i find the acceleration of the system if mass one is 100g and mass 2 is 120g. help!! please...

2. Oct 26, 2004

dekoi

Is this on a ramp?

Or are both massesvertical?

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If they are on a ramp, and m2 is hanging off the ramp:

m1 -->

Fnet = Ft - Fgx (-Ff)
m1a = Ft - FgsinX (-Fnu)

m2 --->

Fnet = m2g - Ft
m2a = m2g - Ft

Equate both (m2a + m1a) to get rid of Ft. Then you can solve for a .

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If they are both vertical:

m1: m1a = Ft - m1g

m2: m2a = m2g - Ft

This is correct if m2 is going downwards, and m1 is forced upwards. However, the answer will be the same either way.

Once again, m1a + m2a to eliminate Ft and find a.

m1a + m2a = m2g - m1g
a = (m2g - m1g) / (m1 +m2)

After typing this, i remembered i wasn't supposed to help you, since you have not shown any of your own work. Please next time, keep that in mind.

Last edited by a moderator: Oct 26, 2004
3. Oct 26, 2004

chathamchick

they are vertical...like hanging on a pole...

4. Oct 26, 2004

dekoi

Refer to me edited post chathamchick.

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