An elevator with a power of 30 kW lifts a load to a height of 20 m per hour. How long does it take

An elevator with a power of 30 kW lifts a load to a height of 20 m per hour. How long does it take for the lift to lift the load to a height of 30 m

Data: N (lift power) = 30 kW (30 * 10 ^ 3 W); h1 (initial lifting height) = 20 m; t1 (initial ascent time) = 1 h (3600 s); h2 (required lifting height) = 30 m.

Constants: g (acceleration due to gravity) ≈ 10 m / s2.

1) Weight of cargo: N = A1 / t1 = m * g * h1 / t1; m = N * t1 / (g * h1) = 30 * 10 ^ 3 * 3600 / (10 * 20) = 540,000 kg.

2) Time to lift the load by 30 m: N = A2 / t2 = m * g * h2 / t2; t2 = m * g * h2 / N2 = 540,000 * 10 * 30 / (30 * 10 ^ 3) = 5400 s (90 min; 1.5 h).