This article will help you understand the difference between body weight and gravity. Understanding this fact is extremely important if you want to successfully solve the problems of the school and any other course of physics, and simply if you are interested in studying the world around us.
Body weight
It is necessary to understand the difference between body weight and gravity. From the school bench, everyone knows: weight, it is the mass multiplied by the acceleration with which the Earth attracts any objects, is one of the basic values in physics. It is a force characteristic with which the body acts on a support. As the latter can serve anything. For example, right now you are most likely acting on a support in the form of a chair, bed or sofa. On the way to work or school, it can serve as the surface of the Earth, the floor of a room or public transport. In turn, the support also responds to your weight, but this will not be discussed in this article, since this situation belongs to the scope of Newton’s third law.
As mentioned above, in order to find the weight of the body, it is necessary to perform a simple calculation, which is a multiplication of two quantities. First you need to determine body weight. To do this, you can use special scales or calculate the mass through density or volume.
For example: the average person’s weight is not more than 75-80 kg, an elephant - more than 5000 kilograms, or 5 tons. The masses of an airplane, rockets or buildings are measured in many millions of kilograms. Once we have found the mass of the object, it is necessary to use the physics reference book in order to find the second part in the equation of body weight - the component of the acceleration of gravity.
As a rule, it is understood as the acceleration with which any object - a person, a car, a standing plane or a parked car would fall to the center of the Earth if all supports would disappear under it overnight. Acceleration of gravity in whole numbers is rounded up to 10 meters per second squared. Now, knowing the mass of the body (it can change, everything depends on the body itself), and also knowing the second component - the acceleration of gravity, we can find the weight of any object. To do this, simply multiply these two simple quantities. The resulting result will be equal to body weight.
Like any other force, body weight is characterized by a special dimension, named after the greatest scientist Isaac Newton.
It is important to remember that the name of a physical quantity characterizing body weight should always be written with a small letter - 1 Newton, 300 Newton. Under certain circumstances, body weight may be zero. For example, the body weight of astronauts in open space and zero gravity inside orbital space stations is zero, because the forces acting on the station when it infinitely falls below the horizon balance any forces with which it is attracted to the surface of the Earth.
It is important to remember that body weight, in contrast to weight, is always positive. For example, a person weighing 60 kg has a weight of about 600 Newtons. Another very important detail: the weight of the body is always applied to the point of contact of the body with the surface. In the figure, this is the point from which the vector P denotes the body weight.
The force of gravity
Gravity is a fundamental physical quantity. If we dwell on a comparison of gravity and body weight, we can see that these values are largely similar. The first is also measured in Newtons, it is also directed towards the center of the Earth (perpendicular to the surface of the support). In order to find gravity, it is also necessary to use the algorithm from the previous task to determine body weight. There are several differences between gravity and weight, but the most important of them are as follows: gravity can never be equal to 0, it acts on the body always and under any circumstances.
You should always remember that gravity has a different application. In other words, the gravity vector comes from the center of mass of any body. The figure shows that the point to which gravity is applied (F weight) is exactly in the middle of the body. If we imagine the weight of the body, then it would be applied to the point of contact with it and the supporting surface. This is the difference between body weight and gravity.
The main thing is to remember that these two physical quantities cannot be called full-fledged analogues. All the difference is in the point of application and the constancy of these forces.