Question

С помощью подвижного блока рабочий поднял груз массой 72 кг. ,на высоту 2,5 метра.Найдите КПД.

Answer 1

1)P=mg=72 кг × 10 Н/кг=720 Н
2)s1=2,5 м ÷ 2=1,25 м
3)Aп=Ps1=720 Н × 1,25 м=900 ДЖ
4)F=mg/2=720 Н/2=360 Н
5)s2=2,5 м
   Аз=Fs2=360 Н × 2,5 м=900 Дж
6)η=(Ап/Аз) × 100 %=1 × 100 %=100 %
Ответ.η=100 %

Answer 2

Calculation of Efficiency (КПД)

To calculate the efficiency (КПД) of the system, we need to know the work input and the work output. In this case, the work input is the energy used to lift the load, and the work output is the gravitational potential energy gained by the load.

The formula to calculate efficiency is:

Efficiency (КПД) = (Work output / Work input) * 100%

Let's break down the calculation step by step:

1. Calculate the work input: - The work input is the energy used to lift the load. - The formula for work is: Work input = Force * Distance - In this case, the force is equal to the weight of the load, which is given as 72 kg. - The distance is the height the load is lifted, which is given as 2.5 meters.

Plugging in the values, we get: Work input = Force * Distance = (72 kg * 9.8 m/s^2) * 2.5 m

2. Calculate the work output: - The work output is the gravitational potential energy gained by the load. - The formula for gravitational potential energy is: Gravitational Potential Energy = Mass * Gravity * Height - In this case, the mass is given as 72 kg, gravity is approximately 9.8 m/s^2, and the height is given as 2.5 meters.

Plugging in the values, we get: Work output = Mass * Gravity * Height = 72 kg * 9.8 m/s^2 * 2.5 m

3. Calculate the efficiency: - Now that we have the work input and work output, we can calculate the efficiency using the formula mentioned earlier.

Plugging in the values, we get: Efficiency (КПД) = (Work output / Work input) * 100%

Now, let's calculate the values:

Work input = (72 kg * 9.8 m/s^2) * 2.5 m = 1764 J Work output = 72 kg * 9.8 m/s^2 * 2.5 m = 1764 J

Efficiency (КПД) = (1764 J / 1764 J) * 100% = 100%

Therefore, the efficiency (КПД) of the system is 100%.

Please note that the efficiency is calculated assuming there are no energy losses due to factors such as friction or heat.