Question: probably easy cuz I'm in Junior High

[engineerwannabe]

I haven't had physics and want to measure tensile failure in hairbands (I'm a girl) by suspending weight from them until they break. I've figured out that I can't measure ultimate tensile strength or breaking strength because I don't have cross-sectional areas (I'm comparing styles). So can I accurately measure tensile failure using the load/weight until they break (in kg) and then convert to N? Do Newton's laws apply? Also, I am confused if I m only measuring weight because it is being pulled down in one direction or am I measuring force, which pulls in two directions?

 

[FredGarvin]

Newton's laws apply. Absolutely.

Weight is a force. Unless you have figured out a way to bend gravity, weight and the applied force are the same thing. You do have me a bit confused with the "force pulls in 2 directions" statement though (you're probably alluding to the fact that forces are vectors and are usually represented in 2D). Usually a tensile test is done so that gravity pulls along the long axis of the specimen. It should all happen along the same line.

Also, don't forget to apply the load very slowly. Don't let the dead weights drop on the specimen.

 

[engineerwannabe]

Thank you! That helps clarify!
I guess I got confused about force reading "A force is similar to a weight, but a force can act in any direction whereas a weight is a force that always acts downwards as a result of gravity." http://www.eng.newcastle.edu.au/eof/content/pdf/module2/sect2.3 .

 

[FredGarvin]

Thank you! That helps clarify!
I guess I got confused about force reading "A force is similar to a weight, but a force can act in any direction whereas a weight is a force that always acts downwards as a result of gravity." http://www.eng.newcastle.edu.au/eof/content/pdf/module2/sect2.3 .

No problem. You're welcome.

Just remember, weight is a specific case of a force.

Good luck in your experiments.