Calculating tension?

Energize · 12 Sep 2006 at 20:43

How do I work out the tension of a piece of string when hanging a picture up on a single nail?

Sleepy · 12 Sep 2006 at 20:46

Free body diagrams

bitslice · 12 Sep 2006 at 21:49

try asking here:
http://www.physicsforums.com/

pulley on a string problem,
I think tension decreases with an increase in deflection

this might be useful ?
(see forces in 2D: ramp)
http://reines.physics.purdue.edu:8080/courses/phys220/posting/lecture/Files/Lecture02.pdf
.

p4radox · 12 Sep 2006 at 22:03

Multiply the mass of the picture by an approximation of mavity: 9.81NKg^-1

Or is that too simplistic?

Energize · 12 Sep 2006 at 22:14

I already know the weight is 50N.

50/50 · 12 Sep 2006 at 22:22

There will only be a vertical component, so weight = tension

Energize · 12 Sep 2006 at 22:59

Ok thanks.

bitslice · 12 Sep 2006 at 22:59

I thought it was this ?

nail
.../\
./...\
+---+
|.....|
+---+

if it's in line you have an Atwood Machine,
= different problem...

.

Energize · 12 Sep 2006 at 23:00

bitslice said:
I thought it was this ?

nail
.../\
./...\
+---+
|.....|
+---+

.

Yes.

Sleepy · 12 Sep 2006 at 23:02

50/50 said:
There will only be a vertical component, so weight = tension

There will be a horizontal component as well. Unless the string is attached only to one part of the frame.

50/50 · 13 Sep 2006 at 00:09

Sleepy said:
There will be a horizontal component as well. Unless the string is attached only to one part of the frame.

Oh I see what you're saying, I didnt see it like that

(pretty embarrasing considering im a im a 3rd year mech eng student!!) .
If its attached to the corners of the frame, with equal angles, just resolve them to find the verticle component, easy.