Question

Электродвигатель подъёмного крана мощностью 6 кВт поднимает груз массой 6 т на высоту 8 м. Определить время подъёма груза, если КПД установки 80%

Answer 1

По закону сохранения энергии 0,8*N*t=m*g*h
t=m*g*h/0,8*N=6*10^3*10*8/0,8*6*10^3=100 c

Answer 2

Calculation of Time for Lifting the Load

To determine the time it takes for the motor to lift a load of 6 tons to a height of 8 meters, we need to consider the power of the motor and the efficiency of the system.

Given: - Power of the motor: 6 kW - Mass of the load: 6 tons - Height: 8 meters - Efficiency of the system: 80%

To calculate the time, we can use the formula:

Time = Work / Power

The work done by the motor can be calculated using the formula:

Work = Force x Distance

The force can be calculated using the formula:

Force = Mass x Acceleration due to gravity

Let's calculate the time step by step.

1. Calculate the force: - Mass of the load: 6 tons = 6000 kg - Acceleration due to gravity: 9.8 m/s^2 - Force = 6000 kg x 9.8 m/s^2 = 58800 N

2. Calculate the work: - Distance: 8 meters - Work = Force x Distance = 58800 N x 8 m = 470400 J (Joules)

3. Calculate the power: - Power of the motor: 6 kW = 6000 W

4. Calculate the time: - Efficiency of the system: 80% = 0.8 - Time = Work / (Power x Efficiency) = 470400 J / (6000 W x 0.8) = 98 seconds

Therefore, it would take approximately 98 seconds for the motor to lift the 6-ton load to a height of 8 meters, assuming an efficiency of 80%.

Please note that the above calculation assumes ideal conditions and does not take into account factors such as friction, mechanical losses, and other inefficiencies that may affect the actual time required for the lifting process.