Physics Question?

Question

Two wires made of the same material are stretched by equal forces. The second wire is twice as long as the first one and also has twice the diameter of the first wire.
If the first wire is stretched by delta L (angular momentum)= 3.6 cm, then by how long is the second wire stretched?

Answer 1

Two wires made of the same material are stretched by equal forces. The second wire is twice as long as the first one and also has twice the diameter of the first wire.
If the first wire is stretched by delta L (angular momentum)= 3.6 cm, then by how long is the second wire stretched?


Why that word angular momentum made its appearance there, I can't guess, but it doesn't belong there.

Let L and 2L be the lengths of the two wires. If the same weight is attached at the end (same force), the strain is given by Stress / Strain = Young's Modulus and thus

Strain = Young's Modulus E / Stress.

Stress = Load / Area

Since Area of the longer wire is 4 times the area of the shorter wire (its diameter is double), Stress is 1/4th and Strain is 1/4th.

However Elongation = Strain x Length = 1/4 x 2 = 1/2

So, the elongation will be 1.8 cm for the longer wire.