A copper wire of length 5.0 m,cross sectional area 7.5 × 10−⁶ m² and Young's modulus 11 × 10¹⁰ N/m² has a 190-kg load hung on it.What is its increase in length? (g = 9.8 m/s²)

Question

Quizplus · Accepted Answer

We can use the formula 
ΔL = (F * L)/(A * Y)
where 
ΔL = increase in length 
F = force applied (190 kg * 9.8 m/s2 = 1862 N) 
L = length of wire (5.0 m) 
A = cross-sectional area of wire (7.5 × 10−16 m2) 
Y = Young's modulus (11 × 1010 N/m2)

Plugging in the values, we get 
ΔL = (1862 N * 5.0 m)/(7.5 × 10−16 m2 * 11 × 1010 N/m2) 
ΔL ≈ 0.0113 m = 11.3 mm

Therefore, the best choice is D, with an increase in length of 11.3 mm.

A Copper Wire of Length 5