Question

Через неподвижное, горизонтально расположенное на некоторой высоте бревно переброшена верёвка. чтобы удержать груз массой 9,9 кг, подвешенный на одном конце верёвки, необходимо тянуть второй конец верёвки с минимальной силой 42 н. С точностью до ньютона определи силу трения, возникающую в данном случае между верёвкой и бревном. При расчётах прими g=10 м/с².​

Answer 1

Решение на фото/////

Answer 2

Problem Analysis

We are given a scenario where a rope is thrown over a horizontal log at a certain height. The rope is used to support a weight of 9.9 kg on one end, while the other end is pulled with a minimum force of 42 N. We need to determine the frictional force between the rope and the log.

Solution

To solve this problem, we can use the concept of equilibrium. In this case, the rope is in equilibrium, meaning the forces acting on it are balanced. The tension force on one end of the rope is equal to the force required to support the weight plus the frictional force on the other end.

Let's break down the forces involved: - Tension force (T): The force applied to one end of the rope. - Weight force (W): The force due to the weight of the object hanging from the rope. - Frictional force (F): The force between the rope and the log.

According to the problem statement, the tension force is 42 N and the weight is 9.9 kg. We can calculate the weight force using the formula:

W = m * g

where: - W is the weight force - m is the mass of the object (9.9 kg in this case) - g is the acceleration due to gravity (taken as 10 m/s²)

Substituting the values, we get:

W = 9.9 kg * 10 m/s² = 99 N

Now, we can set up the equation for equilibrium:

T + F = W

Substituting the known values:

42 N + F = 99 N

Solving for F:

F = 99 N - 42 N = 57 N

Therefore, the frictional force between the rope and the log is 57 N.

Answer

The frictional force between the rope and the log in this case is 57 N.

Answer 3

Problem Analysis

We have a horizontal log or beam at a certain height with a rope thrown over it. One end of the rope is attached to a 9.9 kg weight, and the other end needs to be pulled with a minimum force of 42 N to keep the weight suspended. We need to determine the frictional force between the rope and the log.

Solution

To solve this problem, we need to consider the forces acting on the system. There are three forces involved: the weight of the object (9.9 kg), the tension force in the rope, and the frictional force between the rope and the log.

Let's break down the problem step by step:

1. Calculate the weight force: The weight force is given by the formula: weight = mass * gravity, where gravity is the acceleration due to gravity. In this case, the mass is 9.9 kg and the acceleration due to gravity is 10 m/s² (given in the problem statement). Therefore, the weight force is: weight = 9.9 kg * 10 m/s² = 99 N.

2. Determine the tension force in the rope: The tension force in the rope is the force required to hold the weight suspended. In this case, it is given as 42 N (minimum force required to keep the weight suspended).

3. Calculate the net force on the system: The net force is the vector sum of all the forces acting on the system. In this case, the net force is the difference between the weight force and the tension force: net force = weight - tension = 99 N - 42 N = 57 N.

4. Determine the frictional force: The frictional force is the force between the rope and the log that opposes the motion. In this case, the frictional force is equal to the net force on the system: frictional force = net force = 57 N.

Therefore, the frictional force between the rope and the log is 57 N.

Conclusion

The frictional force between the rope and the log in this case is 57 N.

Please note that the above solution assumes that the rope is inextensible, massless, and there are no other external forces acting on the system.