Question

На какую высоту можно поднять мешок цемента массой 40 кг с помощью подъемника мощностью 400 Вт за промежуток времени 10 с при КПД 80 процентов?

Answer 1

КПД=mgh/Pt
h=Кпд*Pt/mg=0,8*400*10/400=8 метров

Answer 2

Calculating the Height a Cement Bag Can Be Lifted

To calculate the height to which a 40 kg cement bag can be lifted using a 400 W power hoist in 10 seconds with an 80% efficiency, we can use the formula:

Work done = Power × Time

First, we need to calculate the work done by the hoist, which can be expressed as:

Work done = Efficiency × Power × Time

Substituting the given values: - Efficiency = 80% = 0.80 - Power = 400 W - Time = 10 s

We can calculate the work done and then use it to find the height the cement bag can be lifted.

Calculating Work Done

The work done by the hoist can be calculated as follows: Work done = 0.80 × 400 W × 10 s

Work done = 0.80 × 400 W × 10 s = 3200 J

Calculating the Height

The potential energy gained by lifting the cement bag can be calculated using the formula: Potential energy = Mass × Gravity × Height

Where: - Mass = 40 kg - Gravity = 9.81 m/s^2 (standard acceleration due to gravity)

We can rearrange the formula to solve for height: Height = Work done / (Mass × Gravity)

Substituting the given values: Height = 3200 J / (40 kg × 9.81 m/s^2)

Calculating the height: Height ≈ 8.16 meters

Therefore, with a 400 W power hoist operating at 80% efficiency, the cement bag with a mass of 40 kg can be lifted to a height of approximately 8.16 meters in 10 seconds.