Weight / Fulcrum problem

  • Thread starter jschaaf5
  • Start date
  • #1
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Hi,

I am a non-physics type that needs an answer to a fairly simple physics problem (but too complex for me). I need to know where to place a weight on a trailer to arrive at a specific tongue weight (weight at the hitch).

I hope the diagram below is clear.

<------ 48" ------->
-------- W --------

H ------------------------------------- A --------------------- E
<---------------- 96" -----------------> <-------- 64" -------->

Notes:

Line H/A/E is the trailer.

W represents a 1600 lb weight that is 48" wide and is centered over the axle.

The trailer is perfectly balanced at this point (no weight at point H).

H represents the trailer hitch.

A represents the axle (fulcrum).

E represents the end of the trailer.

The distance from H to A is 96".

The distance from A to E is 64".


PROBLEM: How far would the weight (W) need to be moved to the left to arrive at a tongue weight (weight at point H) of 250 lbs?

I hope someone can figure this out. I am stumped.

Thanks in advance.

Jody
 

Answers and Replies

  • #2
Integral
Staff Emeritus
Science Advisor
Gold Member
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The torque about the axels must be the same at all points on the trailer so the force * distance is the same at all points. x is the location of the center of your load.

[tex] 1600 x = 250 * 96 [/tex]

[tex] x = \frac {250lb * 96in} {1600lb} = 15in [/tex]
 
  • #3
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Thanks

That's a big help to me!
 

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