Question

Мотор подъёмного крана мощностью 6КВт поднимает груз массой 6 т на высоту 8 м. Определить время подъёмного груза, если КПД мотора 80%

Answer 1

полезная  работа   A = mgh = 6000*10*8 =480000 Дж

полная работа  An = A/кпд =480000 / 80% *100%=600000 Дж

 

время подъема  t = An/P =600000 Дж / 6000 Вт = 100 с = 1.67 мин

Answer 2

Calculation of Time for Lifting the Load

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

Given: - Motor power: 6 kW - Load mass: 6 tons - Lifting height: 8 meters - Motor efficiency: 80%

To calculate the time, we can use the formula:

Time = Work / Power

The work done by the motor can be calculated as:

Work = Force x Distance

The force exerted by the motor is equal to the weight of the load:

Force = Mass x Gravity

Where: - Mass = 6 tons = 6000 kg (1 ton = 1000 kg) - Gravity = 9.8 m/s^2 (acceleration due to gravity)

Substituting the values into the equation:

Force = 6000 kg x 9.8 m/s^2 = 58800 N

The distance is the lifting height:

Distance = 8 meters

Now we can calculate the work:

Work = 58800 N x 8 meters = 470400 J

Next, we need to calculate the power of the motor in watts:

Power = 6 kW = 6000 W

Finally, we can calculate the time:

Time = Work / Power

Time = 470400 J / 6000 W = 78.4 seconds

Therefore, it would take approximately 78.4 seconds for the motor to lift the 6-ton load to a height of 8 meters, assuming an efficiency of 80%.

Please note that this calculation assumes ideal conditions and does not take into account factors such as acceleration, deceleration, and friction.