Question

Подъемный кран поднимает груз массой 400 кг равноускоренно на высоту 20 м за 2 с. Определите силу тяжести и движущыую силу. Сравните движущую силу, силу тяжести и вес груза.

Answer 1

По 2-ому закону Ньютона
F=ma
в данной задаче дйствуют 2 силы: T и F(тяж), тогда, взяв ось х, напрваленную вверх, получим:
T-mg=ma
s=at^2/2, a=2s/t^2=40/4=10 
T=m(a+g)=400(10+10)=8кН
mg=400*10=4кН
T-mg=4000Н

Answer 2

Calculation of Force and Comparison

To determine the force of gravity and the driving force in the given scenario, we can use the equations of motion.

The force of gravity acting on an object is given by the formula:

Force of Gravity = mass * acceleration due to gravity

In this case, the mass of the load is 400 kg. The acceleration due to gravity is approximately 9.8 m/s^2.

Force of Gravity = 400 kg * 9.8 m/s^2

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

Driving Force = mass * acceleration

In this case, the mass of the load is 400 kg, and the acceleration is the rate at which the load is being lifted, which can be calculated using the formula:

Acceleration = change in velocity / time

The change in velocity is the difference between the final velocity and the initial velocity. Since the load is being lifted uniformly, the initial velocity is 0 m/s, and the final velocity can be calculated using the formula:

Final Velocity = Initial Velocity + (acceleration * time)

In this case, the load is lifted to a height of 20 m in 2 seconds, so the final velocity can be calculated as:

Final Velocity = 0 m/s + (acceleration * 2 s)

Now, we can substitute the value of the final velocity into the equation for acceleration:

Acceleration = (Final Velocity - Initial Velocity) / time

Acceleration = (Final Velocity - 0 m/s) / 2 s

Once we have the acceleration, we can calculate the driving force:

Driving Force = 400 kg * acceleration

To compare the driving force, force of gravity, and the weight of the load, we need to understand their relationships. The weight of an object is the force of gravity acting on it. Therefore, the force of gravity and the weight of the load are the same.

Weight of the Load = Force of Gravity

Now, let's summarize the calculations and compare the forces:

- The force of gravity acting on the load is 400 kg * 9.8 m/s^2. - The driving force required to lift the load is 400 kg * acceleration.

Please note that the acceleration and the driving force will depend on the specific values of the final velocity and time, which are not provided in the question.