Question

16. The length of a metal wire is 10 cm when the tension in it is
20 N and 12 cm when the tension is 40 N. Then natural length
of the wire is (in cm)
a. 6
b. 4
c. 8
d. 9​

Answer 1

Answer:

c) 8cm

Explanation:

We will use a concept called Young's Modulus to answer this question.

Young's Modulus = Y

Y = (Force/Area*Change in Length)

Young's modulus is always constant for a material.

So the two equations can be equated like this

20/Area*(10-l)=40/Area*(12-l)

we can cancel Area and the forces

12-l = (10 - l)*2

12 + l = 20

l = 8

Therefore we conclude the original length to be 8 cm.

Answer 2

Answer:

8

Explanation:

y=F/A*change in length

y1=y2

20/A(10-l) =40/A(12-l)

12-l=20-2l

-l+2l=20-12

l=8