I need help with force/momentum/vectors

  • Thread starter melaku
  • Start date
  • #1
I am asked to do this.

"A uniform beam is attached to two springs scales as shown. The scales read 71 lb and 100 lb respectively. Find the wight of the beam."


I have no idea how to go on about solving this. please someone explain it to me like you would explain it to a child.

Thanks in advance.

Answers and Replies

  • #2
Science Advisor
Gold Member
I'm not being awkward, but I don't understand the diagram one bit.
  • #3
Meir Achuz
Science Advisor
Homework Helper
Gold Member
My guess is that the diagram is meant to show a rod held up by two strings,
one at 45 degrees with a tensiion of 71#, and the other at 60 degrees from the horizontal with a tension of 100#. This is consistent with their being no net horizontal force on the rod.
The net horizontal force is 100 cos 60 - 71 sin 45=0 (as it should).
The net upward force on the stick is 100 sin 60 + 71 sin 45 =87 + 50 = 137#,
which equals the weight of the stick.
  • #4
I reccomended him here for help guys, don't make me look bad:)

That diagram IS funky though