Why do some objects fall faster than others?

Example : A stone falls faster than a piece of paper. In my book it says that the air resistance affects the acceleration of the paper more than it affects the acceleration of the stone. But why does the air resistance affect the acceleration of the paper more than that of the stone?


0|0
5|13

Most Helpful Girl

  • When objects fall through the Earth's atmosphere they get faster and faster until they reach a speed where the upwards force (air resistance) and downwards force (weight) equal each other. At this point the object travels at its fastest speed called terminal speed.

    The paper weighs less so has a smaller force of gravity pulling it down.
    As the paper falls its upwards air resistance increases and soon equals its downwards weight, so it then travels at terminal speed. The stone is heavier and has to be travelling a lot faster before its air resistance is large enough to equal its weight.

    (from BBC bitesize)

    0|1
    0|1
    • Thanks a lot !

    • Show All
    • I don't get this, if the upwards force equals the downwards force, won't that mean that the object is at rest, and not falling at all?
      Speed = acceleration x time, so technically free falling objects will all fall at the same speed, regardless of their weight, cause they have the same acceleration, 9.8 m. s^2 (on Earth). The only difference would be the shape of the falling objects. I think. Correct me if I am wrong.

    • @Squidward
      Equal forces simply means there is no change in velocity (acceleration) Hypothetically, it takes no force for an object to maintain steady velocity. I real life, to many factors are involved to make this observable. Many principles of physics as you are taught are as it would happen in a vacuum (no air resistance, friction, etc)

Most Helpful Guy

What Girls Said 4

  • Actually, absolutely everything that falls will fall at the same rate — strictly speaking, everything falls with the same acceleration, about 9.81 m/s^2 This is do to the pressure of gravity.

    The reason why the stone wall would hit first is because it just went straight down and the paper, falling at the same rate, is drifting down and flying all over the place. In the real world, we have things like air resistance, which is why sometimes heavy things do fall faster. For example, if you drop a feather and you drop a rock, the rock will land first since the feather is slowed down more by the air. If you did the same thing somewhere where there is no air, the feather and the rock would land at exactly the same time.

    (So sorry to go all nerd on you.)

    0|3
    1|0
  • Because it weighs more?

    1|0
    0|1
    • The stone weighs more*

  • because a piece of paper has much higher surface area than a stone. there is simply more space for the air resistance to act upon.

    0|1
    0|0
  • It's not really down to resistance. It's down to the mass of the objects/volume of them/shape etc vs the velocity at which they will fall/be pulled by gravity.

    0|0
    0|1

What Guys Said 12

  • A piece of paper has a larger area than a compact stone, therefore the piece of paper has more area for the drag force to act upon.

    0|4
    0|0
  • I dont remember the exact formulas, haven't taken physics in a few years, but I'll do my best. The objects will accelrate at a similar rate of speed, what is very different i the terminal velocity, or maximum speed. This is a product of acceleration and surface area.
    Change in motion is caused by a surplus of force (s) is. The bigger the difference, the faster the acceleration. Force of gravity is mass x coefficient of gravity (9.8 m/s/s). Surface area is just that, the physical size of the object. The bigger the surface area, the higher the force slowing the objects acceleration.
    A piece of paper will weigh, lets just say 10 grams, and a rock with the same surface area could easily weigh 10 kgs. The rock has a force of 98 N pulling it down while the paper has just.098 N, while having the same amount force slowing it down

    0|0
    0|0
    • The greater the difference between force of gravity (acceleration) and surface area (force of friction), the greater the terminal velocity.

  • Because some objects are lighter, or have more surface area for air resistance. Paper is extremely light and has a huge area for air resistance to affect it, as long as you don't crumple it into a ball.

    Hence, a sheet of paper falls slower than a rock. In a vacuum, they both fall at identical speeds.

    0|0
    0|0
  • Because, air resistance changes due to the velocity, shape, orientation and surface area of the object. It has nothing to do with the weight of the object. Paper has a larger surface area and thus sees a bigger air resistance than the stone. So, the problem becomes,
    Stone: Less air resistance
    Paper: More air resistance

    The one that sees less resistance goes faster.

    0|0
    0|0
  • its because air resistance depends on surface area, a sheet of paper has more surface area than a stone

    0|0
    0|0
  • The stone is more dense than the sheet of paper. Paper, unless you crumple it, has more surface area and yields more wind resistance when dropped. Paper is also incredibly flexible, which makes it's trajectory incredibly lopsided.

    0|0
    0|0
    • Apart from your example, objects fall at the same rate, regardless of other factors.

  • it's having to move more molecules on it's surface than the rock, put it in a vacuum chamber and they both fall at the same speed

    0|0
    0|0
  • Because the paper has a greater surface area. It's the same priciple as a parachute, except the parachute actually traps air under it. Physics is useful!

    0|0
    0|0
  • If air resistance is removed, all objects will fall exactly the same.

    0|0
    0|0
  • The drag of some objects.

    0|0
    0|0
  • The shape of the paper doesn't resist the air as much as the stone. That's why you've never seen a stone-shaped airplane. Also even though they fall at the same speed, they are of different masses, meaning it takes more force for the air to move the stone than it takes the paper.

    0|0
    0|1
  • Aerodynamics, the same reason a parachute falls more slowly in atmosphere when it is open than when it is still in the pack.

    0|0
    0|0
Loading...