Question

Лифт массой 300 кг равномерно поднимается на 10м. Какую работу совершит сила натяжения каната, поднимаются лифт? Какую работу совершит сила тяжести?

Answer 1

А=-Е
E=mgh
E=300*10*10=30000 Дж  или же =30 кДж.
А=30кДж

Answer 2

Calculation of Work Done by Tension Force

To calculate the work done by the tension force in lifting the elevator, we need to consider the formula for work:

Work (W) = Force (F) × Distance (d) × Cosine of the angle between the force and the displacement

In this case, the force is the tension force in the cable, the distance is the height the elevator is lifted, and the angle between the force and the displacement is 0 degrees since the force is acting vertically upwards and the displacement is also vertical.

Given: - Mass of the elevator (m) = 300 kg - Height lifted (d) = 10 m

To calculate the tension force, we can use the equation:

Tension Force (F) = Mass (m) × Gravitational Acceleration (g)

The gravitational acceleration is approximately 9.8 m/s^2.

Let's calculate the tension force and the work done:

Tension Force (F) = 300 kg × 9.8 m/s^2 = 2940 N Work (W) = Tension Force (F) × Distance (d) × Cosine(0°) = 2940 N × 10 m × Cosine(0°) = 29400 J

Therefore, the tension force will perform 29400 Joules of work in lifting the elevator.

Calculation of Work Done by Gravity

The work done by the force of gravity can be calculated using the same formula:

Work (W) = Force (F) × Distance (d) × Cosine of the angle between the force and the displacement

In this case, the force of gravity is acting vertically downwards, and the displacement is also vertical. The angle between the force and the displacement is 180 degrees.

Given: - Mass of the elevator (m) = 300 kg - Height lifted (d) = 10 m

To calculate the force of gravity, we can use the equation:

Force of Gravity (F) = Mass (m) × Gravitational Acceleration (g)

The gravitational acceleration is approximately 9.8 m/s^2.

Let's calculate the force of gravity and the work done:

Force of Gravity (F) = 300 kg × 9.8 m/s^2 = 2940 N Work (W) = Force (F) × Distance (d) × Cosine(180°) = 2940 N × 10 m × Cosine(180°) = -29400 J

Therefore, the force of gravity will perform -29400 Joules of work. The negative sign indicates that the work done by gravity is in the opposite direction of the displacement.

Please note that the work done by gravity is negative because gravity is acting in the opposite direction of the displacement.