Gravity: Why Objects Fall at Same Rate?

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In summary, the reason why all objects fall at the same rate, regardless of their mass, is due to a balance between the force of gravity and the object's inertia. This can be explained through the equation (GmM)/(r*r) = ma, where the mass of the earth, distance from its center, and the acceleration of gravity are all factors. This concept is further supported by an intuitive example of pulling on objects with different masses.
  • #1
Jorge610
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What I've been trying to figure out recently is: I understand that all objects fall at the same rate but don't understand how this makes sense given that things weigh different amounts. For instance, if I were to have a large person sit on my chest they would press much harder against me because of gravity than a small child, leading me to believe that the more massive adult is displaying more gravitational "force", but they fall at the same rate? Why?
 
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  • #2
Jorge610 said:
What I've been trying to figure out recently is: I understand that all objects fall at the same rate but don't understand how this makes sense given that things weigh different amounts. For instance, if I were to have a large person sit on my chest they would press much harder against me because of gravity than a small child, leading me to believe that the more massive adult is displaying more gravitational "force", but they fall at the same rate? Why?

Because a more massive object takes more to accelerate it to the same speed as a less massive object.

The extra pull is exactly balanced by the extra inertia to not move.


Another way to look at it. Forget about gravity for a moment. Turn the experiment on its side. If you attached ropes to a small obejct and to a large object, and then pulled on them, would you expect the more massive object to leap towards you faster than the less massive object?
 
  • #3
I think it's more like this

(GmM)/(r*r) = ma

cancel out the little m (say its the mas of the falling object)
and we have the gravitational constant times the mass of the earth, divided by the distance from its center, squared, as the acceleration of gravity. on most of earth, that's 9.81. :)
 
  • #4
Jorge610 said:
What I've been trying to figure out recently is: I understand that all objects fall at the same rate but don't understand how this makes sense given that things weigh different amounts. For instance, if I were to have a large person sit on my chest they would press much harder against me because of gravity than a small child, leading me to believe that the more massive adult is displaying more gravitational "force", but they fall at the same rate? Why?

Please read an entry in the FAQ thread in the General Physics forum.

Dave has given you a very good "intuitive" reason why this occurs. While a larger mass may have a larger weight, it also has a larger inertia. So the greater force it has just about cancels the larger force one needs to move a heavier object by the same rate.

Zz.
 
  • #5


Gravity is a fundamental force that affects all objects in the universe, regardless of their mass. This means that all objects, regardless of their weight, will fall towards the Earth at the same rate. This is because gravity is an acceleration, meaning that it causes objects to speed up as they fall towards the Earth. This acceleration is the same for all objects, regardless of their mass.

The reason why a larger person may feel like they are exerting more force on your chest is because their weight is distributed over a larger area. This does not change the fact that they are still falling towards the Earth at the same rate as a smaller child. In other words, the gravitational force acting on both the adult and the child is the same, but the distribution of that force may be different.

To understand this concept further, we can look at the equation for gravitational force, which is F = G(m1m2)/r^2. This equation shows that the force of gravity is dependent on the masses of the two objects (m1 and m2) and the distance between them (r). The larger person in this scenario may have a greater mass (m1), but the distance between them and the Earth (r) remains the same. This means that the force of gravity acting on them is the same as it is for the smaller child.

In summary, objects fall at the same rate because gravity is a universal force that affects all objects equally. The weight of an object may affect the way it feels when it exerts force on another object, but it does not change the fact that it is falling towards the Earth at the same rate as all other objects.
 

1. Why do objects fall at the same rate?

Objects fall at the same rate because of the force of gravity. Gravity is a fundamental force that exists between any two objects with mass. The more massive an object is, the stronger its gravitational pull. When objects are dropped, they are pulled towards the center of the Earth by its gravity. This results in all objects falling at the same rate, regardless of their mass.

2. Does air resistance affect the rate at which objects fall?

Yes, air resistance can affect the rate at which objects fall. Air resistance is a force that acts in the opposite direction of motion and can slow down the fall of objects. However, for objects with similar mass and surface area, the effect of air resistance is usually negligible. In a vacuum, where there is no air resistance, all objects would fall at the same rate due to gravity.

3. How does altitude affect the rate at which objects fall?

The rate at which objects fall is affected by altitude due to the change in gravitational pull. As altitude increases, the distance between the object and the center of the Earth increases, resulting in a weaker gravitational pull. This means that objects will fall slightly slower at higher altitudes compared to lower altitudes. However, this effect is minimal and usually only noticeable in extreme altitudes.

4. Does the shape of an object affect its falling rate?

No, the shape of an object does not affect its falling rate. As long as an object has the same mass, it will experience the same gravitational pull and fall at the same rate. The shape of an object can affect the amount of air resistance it experiences, but this does not change the rate of falling.

5. How was the concept of gravity first discovered?

The concept of gravity was first discovered by Sir Isaac Newton in the late 17th century. Newton observed that objects fall towards the Earth and concluded that there must be a force acting on them. He then developed the law of universal gravitation, which states that every object in the universe attracts every other object with a force that is directly proportional to their masses and inversely proportional to the square of the distance between them.

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