Why do heavier things fall faster than lighter things if dropped from a certain height ? related to gravitational force.

Blake Douglas | Certified Educator

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Most of the time, people ask this question with the idea of a Newtonian "feather vs. bowling ball" concept in mind. Based on those terms, the typical answer is correct: two objects will fall at the same speed in a vacuum, and air resistance can appear to make an object fall slower. However, there is a surprising, but more complicated nuance to this problem.

Every action has an equal and opposite reaction. This means that, just as the Earth is exerting a gravitational force on the objects, the objects are exerting a gravitational force on the Earth. Just as much as the objects fall onto the Earth, the Earth falls onto the objects as well. It's just the fact that the Earth is so much larger and more massive that we default to viewing things from the first perspective and not the latter. Nevertheless, the gravitational force exerted on the Earth by the objects cannot be ignored.

Gravitational force is determined by the Universal Gravitation law:

`F = (GmM)/r^2`

where m and M are the two masses involved in the interaction. If we do two separate calculations, one for the mass of the lesser object, and one for the mass of the greater object, we can see that there will actually be a larger gravitational force involved with the more massive object.

This is where most people would interject that, well, yes, the larger mass needs a larger force in order to achieve the same acceleration. But reverse the frame of reference; now let's consider this from the point of view of the objects doing the pulling, instead of the Earth. Now we can see that the force exerted by the larger mass is doing more pulling than the smaller mass. The Earth will "hit" the larger mass first.

Mind you, the scale that this takes place on is smaller than we can actually measure with our current technology. However, it makes sense if you consider it in a different way; If you held a brick and the Moon at the same height and dropped them, which would hit first?

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Related Questions

Inuk Lee | Certified Educator

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There are two ways to answer this question. The first way is to challenge the accuracy of the question, since gravity is constant for all objects. In a windless environment, basically a vacuum, a piece of paper will fall at the same speed as a metal arrow. That sounds like a lie, but it is completely true. The second way to answer the question is by taking into consideration wind resistance. Those items that are streamlined more will fall faster, because these things are able to cut the wind. Those items that are more blunt and cannot cut the wind will move slower.

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pohnpei397 | Certified Educator

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This is not an accurate statement. Heavier objects do not fall faster than lighter objects when they are dropped from a certain height IF there is no resistance from the air. So, if you were in a vacuum, the two things would fall at the same rate.

The only thing that makes a heavier thing fall faster than a lighter thing in real life is the fact that heavier objects usually have more mass per surface area than do lighter things. Because of this, the resistance from the air slows the fall of the lighter thing.

But if both objects had the same ratio of mass to surface area, they would fall at the same rate.

So, the only thing that makes a lighter thing fall more slowly is the resistance from the air.

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sid-sarfraz | Student

Gravity is a natural force which pulls objects to the surface of the earth. Weight is the main key in the gravitational force. Heavy objects due to their heavy weight fall faster as compared to the light weight objects that fall slowly due to their light weight.

For example if throw a paper and a ball from the same height. The ball will reach the surface of the earth first and then the paper will touch the earth. Paper is light weight and it falls quickly due to air resistance. Ball is heavy and will reach the surface of the earth faster. As friction in air is less.

mohem | Student

They in fact do not, but because our atmosphere consist of Gas rather than vacuum, it adds a resistive to the larger surface area thus the effective gravitational force is opposed by this resistance. Think of a paper and small rock where the paper surface area greater than the solid rock, where the rock is more aerodynamic than the paper.

ahmedrehan | Student

Because of their higher mass and greater momentum as a result .

givingiswinning | Student

the heavier item would hit the ground first

crystaltu001 | Student

It's based on the mass of the object. If 2 different things that each weighed differently were dropped the heavier item would hit the ground first since it has more mass and the lighter things tend to float for a little bit before it actually hits the ground

zumba96 | Student

Based on the mass if you dropped a feather from a 500 foot height and a bowling ball from the same height of course the bowling ball would hit the ground first because the mass would create more acceleration

atyourservice | Student

they drop at the exact same rate, it is just that earth has an air resistance which cause lighter things to float a little bit

aeherb3 | Student

This can be answered best by using the equation Force= mass x acceleration.

Please note, that there are two environments in which there will be different answers.  In a vacuum, that is, in the absence of friction, both objects will fall at the same time. Surface area and mass become important however as we imagine this scenario on our earth.  On earth where every object experiences gravity, the two objects will fall at different rates.

Let's imagine an elephant and a feather, both dropped from the top of a very tall building.  When you drop the objects, they are experiencing the same acceleration due to gravity, but due to their different masses, they are both exerting different amounts of "downward" force.

Elephant= 1000 kg

Feather= 1kg

Acceleration due to gravity= 9.8m/s/s``

Downward force being exerted by elephant:  F= (1000kg) x (9.8m/s/s) = 9800N

Downward force being exerted by feather: F=(1kg) x (9.8m/s/s) = 98N

The next thing you have to consider is terminal velocity- Terminal velocity is when acceleration stops (this is when the force of gravity and the force of air resistance are balanced).  The feather requires much less air resistance for it to reach terminal velocity.  The elephant requires a  great amount of air resistance to slow and come to a terminal velocity.

You can experiment with this phenomenon by designing a parachute device- try to make one that reaches terminal velocity quickly so as to protect it's "passenger" (try to save a raw egg from cracking).  You can make your parachute with cheap household materials and experiment with different masses of your parachute device, different sizes of parachute, and different design characteristics.  Keep in mind the principals of Newton's Laws throughout your experimenting.

Happy engineering!

boyboy-2144 | Student
They have more mass:)
nb-zhu | Student

Objects that are heavier will fall faster than objects that are lighter

I did an experiment by manipulating the falling object's mass, and the results confirm this statement.

Heavier objects have a greater terminal velocity because they accelerate faster, and have a greater downwards force, meaning that the object requires a greater air resistance to reach that terminal velocity. When the object reaches terminal velocity, there is zero acceleration, so when the objects mass is increased, the terminal velocity is also increased. This means it takes longer for that object to reach its terminal velocity, and during that time it is constantly accelerating. So yes objects that are heavier do fall faster!

x-sumit-x | Student

it is beacause the heavier objects can attarct to the gravity faster

Due to the effect of gravitational force all bodies fall with the same acceleration and speed in vaccum but in some other propagating media as the force acting on the body is directly proportional to its mass and also air friction comes into play.

As a result of which the body acquiring higher momentum<as a result of higher mass as p=mv> falls quicker than the lighter body...also surface area and densities are factors on which this depends..........

asmathwiz | Student

I agree with #3.Both fall at the same time.

aznboy578 | Student

I agree with #1 heavier objects do not fall faster than lighter objects. This will only happen if you do this. Paper and a rock which one falls faster the rock. Only because the surface area.

vasudanainakumari | Student

as hevier objects posses more mass when compared to lighter objets... each and every parctile of the object experience gravitational force

where as in case of light objects  it has less mass....

and aslo lighter and heavier both experience air pressure on them but hevier objects can withstand against the air pressure as its mass is high..

where as lighter ones cant withstand the presure so they move along with air....

valie77 | Student

because of gravity...

but did you know that if you threw a one pence coin of the iffle tower in france it could kill a person at the bottem by hitting them on the head !!!!!!!!!

manish001 | Student

No,heavy things dont fall faster than the lighter ones.Its just an illusion.but in earth's surface,due to air resistance the object having greater surface area faces greater air resistence but in vaccum both lighter as well as heavier objects fall simultaneously.Due to air resistence,objects like feather falls slowly as it is highly affected by the resistence provided by air.

heavier objects fall faster than lighter objects only in the presence of air. Newton illustrated this in his "Feather and Coin" experiment.

shivangi128 | Student

All objects fall at same rate. There if you will fall an elephant and mice, they both will reach at same time

only difference can be due to the surface area of the object, more surface area encounters more air resistance resulting in less speed.

but IN VACCUM when objects with different surface ares fall, they fall at same speed

ngyunhui | Student

In a vacuum, heavy things fall at the same rate as light things. This fact of Newtonian physics has been proved many times over. During the Appollo 15 mission a feather and a hammer were dropped and this was demostrated very graphically.

However, in an atmosphere heavier things generally fall faster than lighter things although the opposite can also be true. This isn't because gravity works any differently, but because of "drag" - air friction acting to slow the falling object. A feather has much more surface area compared to its weight than a hammer does, and so in an atmosphere it falls slower. Conversely, a bowling ball is much lighter than an airplane, but due to aerodynamic factors the ball would fall much faster

rockonhunter | Student

the heavyer the mass is the faster it will drop

aabbeir | Student

weight is the key. In vacuums and space they fall at the same time because they are in free fall.

Why do we always talk about "falling"!  This description only lends itself to confusion.  The "falling" experiment was only a means to prove something which is already easy to explain in its base terms.

Gravity is a force of attraction between any instances of mass in the universe, which when acting on any other mass, will pull toward the other.  Large things like planets seem to be doing all the pulling in space, but gravity is a constant and its force is just a product of the parts involved.  All things have this gravitational constant at an atomic level.

The only resistance of real importance here is that of a mass's desire to stay in place.  An object at rest will tend to stay at rest, more-so given its mass related to the force acting on it.  Larger masses have greater susceptibility to the effects of gravitational force than smaller masses, but also greater resistance to its acceleration effects!  "Heavy" things are actually LESS likely to "fall"!!!  They do so, begrudgingly!

This has nothing to do with air resistance or weather balloons.  Its just Newton's basic natural principle.  The force is the "product" (m1 x m2) of the masses, but the resistance to change is the factor that makes "heavy" objects acted on by a single body actually accelerate toward the gravitational center of that body at the same rate as its "lighter" counterpart, which may have less "mass", but also therefore less "resistance" to said gravity. Equal!

jess112 | Student

heavier objects do fall faster than lighter objects do as the heavy wait pulls the object down to the ground by gravity and the lighter object gently floats to the ground very slowly.

this comment is not completely accurate but thats my point of veiw and my opinion

joy1495 | Student

This question is related to weight. Weight is defined as the amount of force by which earth pulls an object towards it. We know; W=mg where, m=mass and g=9.8 metre per second squre. So if a heavier and a lighter object is thrown simultaneously from same height the heavier object falls quickly because it has more mass than the lighter object and the g is always constant.

deepakkumarkaran | Student

Rather than 'lighter 'or 'heavier' , I use 'less dense' or 'more  dense' objects and  I also pressume a medium of air through which the objects fall.

The falling free in vaccum and falling through air are 2 slightly different concepts. Air acts as a buyant liquid on the falling objects. In liquid all objects of leser density than the liquid floats. There is the principle of Archemedes supporting this. Similarly any thing which is less dense than air does not fall but float in air. This is because air makes  a  buoyant force which thrusts up  the obect with less density than that of  air.

Secondly all things in air looses a weight which is equal to the volume of the air dispelled by the object by the principle of Archimedes. Therefore, the lighter density objects having larger volume loose more weight by the buoyant force of air (we call this the air resistance under the context) compared to the equivalent mass of denser objects. That is the reason why we see the lighter objects fall slower. This could be seen and confirmed (i)from the example of solid iron  and a flywood of identical mass falling from around 100 metr height and (ii) or solid iron and a solid flywood of identical volume and shape falling from 100 meter.

Conclusion: The less dense objects fall slower than more dense objects in the medium of air. But in vaccum they should fall with equal velocity, irrespective of their shape, mass or density obeying the Law of gravitation.

deepakkumarkaran | Student

This is not an accurate statement.  Heavier objects do not fall faster than lighter objects when they are dropped from a certain height IF there is no resistance from the air.  So, if you were in a vacuum, the two things would fall at the same rate.

The only thing that makes a heavier thing fall faster than a lighter thing in real life is the fact that heavier objects usually have more mass per surface area than do lighter things.  Because of this, the resistance from the air slows the fall of the lighter thing.

But if both objects had the same ratio of mass to surface area, they would fall at the same rate.

So, the only thing that makes a lighter thing fall more slowly is the resistance from the air.

Can this be as per Archimedis principle and concept of buoyancy?

javaria95 | Student
This is not an accurate statement. Heavier objects do not fall faster than lighter objects when they are dropped from a certain height IF there is no resistance from the air. So, if you were in a vacuum, the two things would fall at the same rate. The only thing that makes a heavier thing fall faster than a lighter thing in real life is the fact that heavier objects usually have more mass per surface area than do lighter things. Because of this, the resistance from the air slows the fall of the lighter thing. But if both objects had the same ratio of mass to surface area, they would fall at the same rate. So, the only thing that makes a lighter thing fall more slowly is the resistance from the air.

thevinn | Student

The only difference is wheather they are subject to air, and if so, are they the same size?If there is air I is possible to get lighter object to fall faster, if there is no air. Then they will fall at the same speed. (If released at the same time.)

friendjoy | Student

it is related to gravitational force which acts upon the bodies of earth...

neela | Student

Rather than 'lighter 'or 'heavier' , I use 'less dense' or 'more  dense' objects and  I also pressume a medium of air through which the objects fall.

The falling free in vaccum and falling through air are 2 slightly different concepts. Air acts as a buyant liquid on the falling objects. In liquid all objects of leser density than the liquid floats. There is the principle of Archemedes supporting this. Similarly any thing which is less dense than air does not fall but float in air. This is because air makes  a  buoyant force which thrusts up  the obect with less density than that of  air.

Secondly all things in air looses a weight which is equal to the volume of the air dispelled by the object by the principle of Archimedes. Therefore, the lighter density objects having larger volume loose more weight by the buoyant force of air (we call this the air resistance under the context) compared to the equivalent mass of denser objects. That is the reason why we see the lighter objects fall slower. This could be seen and confirmed (i)from the example of solid iron  and a flywood of identical mass falling from around 100 metr height and (ii) or solid iron and a solid flywood of identical volume and shape falling from 100 meter.

Conclusion: The less dense objects fall slower than more dense objects in the medium of air. But in vaccum they should fall with equal velocity, irrespective of their shape, mass or density obeying the Law of gravitation.

krishna-agrawala | Student

The speed at which things fall when dropped from certain height is the determined by the resultant of two forces acting on the body. The first is the gravitational force acting on the body. Opposing this force is the air resistance offered to the movement of the body.

Under the effect of gravitational force alone all bodies will fall with the same acceleration and speed, as the force acting on the body is directly proportional to its mass. However the air resistance offered is dependent on surface area and shape of the body. when two bodies of same mass but different densities are dropped from a given height, the body with lower density, due to its greater size and surface area than the denser body, will experience greater resistance from air and therefor will have lower speed.

Even for objects of same density the ratio if surface area to mass increases as the size is reduced. Therefore objects of smaller size experience greater air resistance per unit mass as compared to that of a bigger size. This the reason why a small particle of dust taken from a stone will fall at much slower speed as compared to the stone.

mkcapen1 | Student

Not at all. Two objects falling from the same place despite their weight differences will hit the ground at the same time.  You can test this theory by taking a tennis ball and a golf ball and standing on a table.  Hold your arms out at the same height and drop the objects.  If your arms are held at the same height the balls will hit the ground at the same time.  The times when this would not occur is if one object is flat paper and the other object is a ball.  The paper will have more resistance because of its shape.