A wire has a final length of 6.0 m after undergoing a strain of 200%. What is the original length of the wire?

 Question 19

A wire has a final length of 6.0 m after undergoing a strain of 200%.

 

What is the original length of the wire?

A 1.5 m                       B 2.0 m                       C 3.0 m                       D 4.0 m

 

 

 

Reference: Past Exam Paper – November 2015 Paper 11 Q23

 

 

 

Solution:

Answer: B.

Let the original length = L

Extension = 6 – L

Percentage strain = (extension / Original length) × 100%

200 % = ((6 – L) / L) × 100%

(6 – L) / L = 200/100

(6 – L) / L = 2

6 – L = 2L

6 = 2L + L

L = 6/3 = 2 m