cocospaniel said:nerd007 said:Does anyone know how to solve questions like these? I always get them wrong.
Two wires P and Q are made from the same material.
Wire P is initially twice the diameter and twice the length of wire Q. The same force, applied to
each wire, causes the wires to extend elastically.
What is the ratio of the extension in P to that in Q?
A.1/2 B.1 C.2 D.4
Thanks a lot. You guys have been great =D
I have wrote this many times
Use the young Modulus formula. E= Fl/Ae
Equation 1 - Ee= F(tension)*l/A
Equation 2 - Ee= F(tension)*2l/0.5A = 4Fl/A
Since it's the same wires, young modulus is the same, (e) is the same. So equate both equations.
Fl/A=4Fl/A Do some algebraic manipulation and you'll get 4/1
Oops.. sorry. Thanks =D