With a uniform lifting of a steel beam by a tower crane to a height of 25 m, a work of 30 kJ was performed. Determine the volume of the straw.
Data: the movement of the steel beam is uniform; h (the height to which the beam was raised) = 25 m; A (work done by a tower crane) = 30 kJ (30 * 10 ^ 3 J).
Constants: g (acceleration due to gravity) ≈ 10 m / s2; according to the condition ρс (steel density) = 7800 kg / m3.
To determine the volume of the raised steel beam, we use the formula: A = ΔEp = m * g * h = ρс * V * g * h, whence V = A / (ρс * g * h).
Calculation: V = 30 * 10 ^ 3 / (7800 * 10 * 25) = 0.0154 m3 or 15.4 dm3.
Answer: The volume of the beam is 15.4 dm3.
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