Question

Подьемный кран равномерно поднимает гранитную глыбу массой 3 т на высоту 15 м в течение 2 мин.Какова полезная мощность двигателя подьемного крана? (3,75 кВт)

Answer 1

P=A/t
 A=Fh=mgh
 P=mgh/t 
 m=3000 кг
 h=15 м
t=120 c 
 P=(3000*10*15)/120=3750 Вт
надеюсь помогла)))

Answer 2

Calculation of Useful Power of the Crane's Engine

To calculate the useful power of the crane's engine, we can use the formula:

Useful Power = Work Done / Time

The work done by the crane is equal to the force applied multiplied by the distance traveled. In this case, the force applied is the weight of the granite block and the distance traveled is the height it is lifted.

Given: - Mass of the granite block = 3 tons = 3000 kg - Height lifted = 15 m - Time taken = 2 minutes = 120 seconds

First, let's calculate the work done by the crane:

Work Done = Force x Distance

The force applied by the crane is equal to the weight of the granite block, which can be calculated using the formula:

Weight = Mass x Gravity

Where: - Mass = 3000 kg - Gravity = 9.8 m/s^2 (approximate value)

Weight = 3000 kg x 9.8 m/s^2 = 29400 N

Now, let's calculate the work done:

Work Done = 29400 N x 15 m = 441000 J

Next, we can calculate the useful power of the crane's engine:

Useful Power = Work Done / Time

Useful Power = 441000 J / 120 s = 3675 W = 3.675 kW

Therefore, the useful power of the crane's engine is 3.675 kW.