# What is the elongation of a steel bar with a cross-section of 0.8 cm squared

What is the elongation of a steel bar with a cross-section of 0.8 cm squared and 10 m long under the action of a load weighing 500 kg? (E = 220 GPa)

Data: S (section of a steel bar) = 0.8 cm2; l (steel bar length) = 10 m; m (weight acting on the steel bar) = 500 kg.

Constants: g (acceleration of gravity) = 10 m / s2; by the condition E (Young’s modulus, steel) = 220 GPa = 220 * 10 ^ 9 Pa.

SI system: S = 0.8 cm2 = 0.8 * 10-4 m2.

The elongation of the steel bar is determined from the equality: Δl / l0 = F / (E * S), whence Δl = F * l0 / (E * S) = m * g * l0 / (E * S).

Calculation: Δl = 500 * 10 * 10 / (220 * 10 ^ 9 * 0.8 * 10 ^ -4) = 0.00284 m = 2.84 mm.

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