Why do heavier things fall faster than lighter things, does it have something to do with gravity?

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shelly1689's profile pic

shelly1689 | High School Teacher | (Level 1) Adjunct Educator

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Rate of motion, including falling, is determined by the second law of motion

v2 = v1 + a△t,

where v1 is initial velocity, v2 is final velocity after a period of time, t, and a is acceleration. Note that there is no mass quantity in this equation, indicating that the mass of an object is irrelevant to its motion in a frictionless environment.

Applying this to a falling object, presumably in free fall (no initial velocity), with a being the acceleration due to gravity, we see that - again in a frictionless environment - all objects will fall at the same rate (Galileo actually proved this).

However, in an environment where friction is present, different objects will fall at different rates, depending on the degree to which friction opposes their motion. Air resistance, a form of friction known as fluid drag, is a function of surface area; the greater the surface area, the greater the drag, and hence the greater the resistance to motion.

The issue is a little more complicated than this, but, in a nutshell, objects with greater surface area will experience greater fluid drag, which would tend to cause them to fall more slowly.

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growley52 | College Teacher | (Level 1) Adjunct Educator

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Feather Vs Hammer, on the moon

The first two answers are complete.  I'd just put in the formula:

`F(g) = G((m_(1))(m_(2)))/r^2`

` `Where G has the value given in the third answer.  At ground level on the earth, this reduces to `F(g) =m_(1)g`

where g is the ratio of the mass of the earth and the square of its average radius.

`g = m_(2)/r^2`

` `

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jyurkonis | (Level 2) Adjunct Educator

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At a practical level, for a person observing two things falling on earth over a relatively short distance, there should be no real difference in the rate at which they fall, as long as the objects are approximately the same size and shape.

The rest of the story can get very complicated.

It is true that mass will make an observable difference for objects the size of planets, moons or large asteroids but the term "falling" would never be used to describe the action of their movements towards each other.

There are many things that act on an object falling on earth (think of a helium balloon compared to one filled by air from your lungs or how a hot air balloon will fall more quickly as the air inside of it cools off, or how quickly a helicopter will fall if you shut it's engine off, or even how raindrops fall much faster than snowflakes)

If a third grader and a sixth grader both jumped off of a 4 foot wall at the same time (not recommended), or if a heavy baseball and a lighter tennis ball were dropped from shoulder height at the same time, there would be no noticeable difference in when they hit the ground.

For us humans here on earth, what we call air resistance makes the biggest difference when it comes to how quickly something hits the ground.

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joyclarke | (Level 1) Adjunct Educator

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The rate of fall of an object is 9.81 m/sec2, and this applies to both "light" and "heavy" objects.  Therefore, in the absence of resistance (a force acting in the opposite direction), they would both hit the ground at the same time if dropped from the same height at the same time.

If it is an environment in which there is resistance from the air, referred to as a free-fall environment, the heavier object will be observed to reach the ground first.

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gsenviro | College Teacher | (Level 1) Educator Emeritus

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This is an incorrect statement. All objects fall at the same rate in the absence of air resistance, i.e. in a vacuum. 

In a vacuum, the weight of the object (given as mass times acceleration due to gravity) is the same as the force on it (given as mass times acceleration),

i.e. m x a = m x g

i.e., a = g

which means irrespective of the weight of the object, all objects will fall with the same acceleration (in an absolute vacuum).

However, in real life, objects do encounter air resistance and that's what may make heavier objects 'appear to' fall faster than lighter objects. The heavier objects, because of their large density and smaller size, will feel less air resistance as compared to lighter objects. However, objects with the same ratio of mass to surface area will fall at the same rate.

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llovejoy | Middle School Teacher | eNotes Newbie

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Stand on a second floor balcony and drop a marble and a flat sheet of paper at the same time and yes the marble will fall faster than the paper, however this is not due to gravity, but due to air resistance. A flat sheet of paper takes up a lot more space than a small round marble and there is therefore a lot more area for air to push against, slowing down the papers fall.  

If we did not have any air resistance, (if we could drop the marble and the paper in a ‘vacuum’) then the marble and the paper would fall to the ground at exactly the same time. This IS because of gravity. Gravity, (specifically gravity related to things falling to the ground on EARTH) is about the Earth PULLING objects towards itself, and NOT about how heavy those objects are. The Earth, because it is so massive, attracts or pulls everything towards itself, and it does this with exactly the same amount of force for every object no matter what there size and shape. Therefore without other influencing factors (such as air resistance) the marble and paper would fall (or rather be pulled) toward Earth at exactly the same rate and force.

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kleynhansj | eNotes Newbie

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Aristotle said that there are 4 elements: Earth, Wind, Water, Fire. Objects made of earth (like a rock) will want to go the center of the universe (center of the Earth). Things made of fire want to go to the place where fire is. I guess this would be the Sun – or somewhere up. Aristotle also said that a heavier object will fall at a faster speed.

acceleration = mass and force 

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efranklin30 | eNotes Newbie

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Heavier objects just appear to fall faster. Lighter in weight objects appear to fall slower simply because the air resistance had greater affect on that object than on a heavy object. If there was no air resistance all objects would fall at the same speed. 

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indikawicks | eNotes Newbie

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  • Every planetary body has its own gravitational attraction force which attracts objects towards its center. 
  • Gravitational force on the earth is denoted by 'g' and it equals to  9.80665 m/s2.
  • The equation for calculating gravitational force is as follows. the following:

         

        Where F is the force, m1 and m2 are the masses of the objects                         interacting, r is the distance between the centers of the masses                      and G is the gravitational constant that is  6.674×10−11 N⋅m2/kg2.

  • If we calculate the gravitational force acting on a object falling to earth using above equation, taking m1 as the mass of the earth (which is constant) and m2 as the mass of the object falling to the earth, it is evident that gravitational F is proportionately increases, if we increase the mass of the object. Also, the distance center of the earth to the center of the mass in inversely proportionate to the gravitational force. More the distance, lesser the force.
  • Therefore, if we release two objects having two masses,  it is the  object having heavier mass that will fall faster than an object having lesser mass. 
  • Therefore, heavier things fall faster than lighter things because of the gravitational force acting on heavier mass creates higher acceleration towards the earth. 

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