A wire of radius 0.3cm is used to lift a block of 1.5kg. Calculate the stress introduced into the wire [ take g = 10m/s\(^2\)]
A
53 x 10\(^{-4}\)Nm\(^{-2}\)
B
5.3 x 10\(^{-4}\)Nm\(^{-2}\)
C
53 x 10\(^4\)Nm\(^{-2}\)
D
5.3 x 10\(^4\)Nm\(^{-2}\)
Verified Correct Answer: C.
Physical Principles & Numerical Solution
\(F = m \cdot g = 1.5 \, \text{kg} \times 10 \, \text{m/s}^2 = 15 \, \text{N}\)
\(A = \pi r^2 = \pi (0.003 \, \text{m})^2 = \pi (9 \times 10^{-6}) \approx 2.827 \times 10^{-5} \, \text{m}^2\)
\(\text{Stress} = \frac{F}{A} = \frac{15 \, \text{N}}{2.827 \times 10^{-5} \, \text{m}^2} \approx 5.299 \times 10^5 \, \text{Pa}\)
Source: Myschool Past Questions Archive (Record #74482)