How to find the power of resistance

When moving any subject on the surface or in the air there are forces that prevent this. They are called resistance or friction. In this article we will tell how to find the power of resistance, and consider the factors affecting it.

To determine the resistance force, it is necessary to use the third law of Newton. This value is numerically equal to the strength that you need to attach to force evenly move the object to a flat horizontal surface. This can be done with a dynamometer.

The impedance force is calculated by the formula F \u003d μ * M * G. According to this formula, the desired value is directly proportional to the mass of the body. It is worth considering that for the correct counting it is necessary to choose μ - the coefficient depending on the material from which the support is made. Take into account the material of the subject. This coefficient is selected on the table. A constant G is used to calculate, which is 9.8 m / s2.

How to calculate resistance if the body is not moving straight, but by the inclined plane? To do this, enter the COS angle to the initial formula. It is from the angle of inclination that depends on the surface and resistance of the surface of the body to the movement. The formula for determining friction on the inclined plane will have such a form: F \u003d μ * M * G * COS (α).

If the body moves at an altitude, then the force of friction is valid on it, which depends on the speed of the subject. The desired value can be calculated by the formula F \u003d V * α. Where V is the speed of the object, and α is the resistance coefficient of the medium. This formula is suitable exclusively for bodies that are moving at low speed. To determine the strength of resistance of jet aircraft and other high-speed units, the other is used - f \u003d v2 * β. To calculate the friction force of high-speed bodies, the square of the velocity and the coefficient β is used, which is calculated for each item separately. When the object is moved to a gas or liquid when calculating the friction force, it is necessary to take into account the density of the medium, as well as the mass and volume of the body.

Resistance to movement significantly reduces the speed of trains and cars. And two types of forces act on the driving items - permanent and temporary. The total force of friction is represented by the sum of two magnitudes. To reduce resistance and increase the speed of the machine, designers and engineers are inventing a variety of materials with a sliding surface from which the air is repelled. That is why the front part of the high-speed trains has a streamlined form. Fish moves very quickly in water due to a streamlined body covered with mucus, which reduces friction.

Not always the power of resistance adversely affects the movement of cars. To pull the car from the dirt, you need to pour sand or crushed stone under the wheels. Due to the increase in friction, the car perfectly copes with swampy soil and mud.

Resistance to the movement in the air is used during parachute jumps. As a result of the resulting friction between the dome and air, the speed of the parachutist is reduced, which makes it possible to engage in parachute sports without prejudice to life.