Question

Подъемный кран поднимает груз массой 5 тонн.Мощность двигателя 15 кВт.Коэффицент полезного действия крана 80%.Определите скорость подъема груза.

Answer 1

Дано
m = 5 т = 5000 кг
N = 15кBт = 15000 Bт.
η(КПД) = 80% = 0.8
Найти V - ?
Решение
N = A/t
Пусть практическая работа (Ап),
а теоретическая (Ат)
Ат = 15000 Bт / 1 = 15000 Дж.
Ап = Aт * η = 15000Дж * 0.8 = 12000 Дж.
A = F / S
S = A / F  = 12000 Дж / 50000 = 0,24 м/с
Ответ: V = 0,24 м/c или же 0,864 км/ч.

Answer 2

Calculation of the lifting speed of the crane

To determine the lifting speed of the crane, we need to consider the power of the engine, the weight of the load, and the efficiency of the crane.

Given information: - Mass of the load: 5 tons - Engine power: 15 kW - Efficiency of the crane: 80%

The lifting speed of the crane can be calculated using the formula:

Lifting speed = (Power of the engine × Efficiency) / Weight of the load

Substituting the given values into the formula:

Lifting speed = (15 kW × 0.8) / 5 tons

To calculate the lifting speed, we need to convert the units of power and weight to a consistent system. Let's convert the power from kilowatts (kW) to watts (W) and the weight from tons to kilograms (kg).

1 kW = 1000 W 1 ton = 1000 kg

Converting the units:

Power of the engine = 15 kW × 1000 = 15000 W Weight of the load = 5 tons × 1000 kg = 5000 kg

Now we can calculate the lifting speed:

Lifting speed = (15000 W × 0.8) / 5000 kg

Simplifying the equation:

Lifting speed = 12000 W / 5000 kg

Lifting speed = 2.4 m/s

Therefore, the lifting speed of the crane is 2.4 meters per second.