Mechanics

# Weight is different from mass

Weight is different from mass because the latter is associated with inertia, while the former is the gravitational force of attraction that the planet exerts on the object.

When we drop an object, we see that it moves towards the Earth because the weight force, also called the gravitational force, pulls the body downwards. As weight is a gravitational force of attraction, we cannot confuse it with mass. Although in everyday life some people treat mass and weight as being the same thing, in physics they are totally different. The mass of a body is associated with inertia, while weight is the gravitational force of attraction that the planet exerts on the object.

Weight and Newton’s third law

As you already know, for every action there is a reaction. If the Earth attracts a body with a gravitational force called weight, then the body attracts the Earth with a force of equal magnitude, but in the opposite direction.

Briefly, we can write:

Modulus : P=m .g (where g is the local acceleration of gravity and m is the mass of the body).

Direction : on the line joining the center of the body and the center of the planet (vertical).

Direction : towards the center of the planet (down).

The weight depends on where it is determined

The weight of a body depends on where it is determined. An explanation can be found in the weight equation itself, after all it depends on the acceleration of gravity and if it varies, the weight will vary proportionally.

Consider a body of weight P T here on Earth. If this body is taken from Earth to another planet, whose acceleration due to gravity (g) is greater, the attraction (weight) will also be, that is, the weight of the body on the planet (P P ) will be greater than its weight. body on Earth (PT ) . Let’s look at some examples:

The acceleration of gravity on the planet Jupiter is 2.37 times greater than that of Earth, so the weight of bodies on Jupiter is 2.37 times greater than the weight of the same bodies on Earth. The acceleration of gravity on Earth is 6 times greater than the acceleration of gravity on the Moon, so the weight of a body on Earth is 6 times greater than the weight of the same body on the Moon.

Note: the mass of the body does not depend on where the object is. The mass of a body on Jupiter, on Earth and on the Moon is exactly the same.

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