Question

С помощью неподвижного блока равномерно подняли груз массой 45 кг на высоту 3м. Каков КПД блока, если приложенная сила была равна 500Н? Есть ли в условии лишние данные? решите плиз!

Answer 1

груз массой 45 кг создаёт силу тяжести 45 * 9,81 = 441,45 Н.

КПД = (441,45 / 500) * 100 = 88,3 %

Если равномерно подняли груз, то на высоту 3 м - лишнее данное.

Answer 2

Problem Analysis

To calculate the efficiency of the block, we can use the formula for efficiency, which is the ratio of useful work output to the total work input. The useful work output is the work done against gravity to lift the mass, and the total work input is the work done by the applied force.

Calculation

The useful work output can be calculated using the formula: useful work output = force × distance. In this case, the force is 500N and the distance is 3m.

The total work input can be calculated using the formula: total work input = force × distance. In this case, the force is 500N and the distance is 3m.

Efficiency Calculation

The efficiency can be calculated using the formula: efficiency = (useful work output / total work input) × 100%.

Let's calculate the efficiency using the given data.

Solution

The useful work output is: useful work output = force × distance = 500N × 3m = 1500J.

The total work input is: total work input = force × distance = 500N × 3m = 1500J.

Now, we can calculate the efficiency: efficiency = (useful work output / total work input) × 100% = (1500J / 1500J) × 100% = 100%.

Conclusion

The efficiency of the block in this scenario is 100%. This means that all the work done by the applied force was converted into useful work output, lifting the mass against gravity.

Extra Data

The given data of the mass of the load (45 kg) was not necessary for calculating the efficiency of the block. The efficiency depends on the work done by the applied force and the distance over which it is applied, regardless of the mass being lifted. Therefore, the mass of the load can be considered as extra data in this context.