Surely this bird must be from another world for this to be possible…
Okay I misled you. I will ask you a more relevant question. If you dropped a feather and a bowling ball from the same height, at the same time – what would you expect? You would expect the bowling ball to hit the floor a lot faster than the feather, right? Is this true for all cases?
We must talk about some not so interesting fundamentals of Physics, to move on and understand more spectacular things so bear with me.
Newton’s second law states that the force on an object is its mass times by its acceleration (F = ma).
When an object is falling it has certain forces acting on it. In free-fall, there are two. Its weight; F = mg (mass x gravity), which pulls the object down towards Earth, and air resistance which resists the force of the weight by acting against it.
The ball in Figure 1 is in free-fall. Since it is falling, the overall force acting on it is its weight, right? Weight is F = mg.
Remember Newton’s Second Law (F = ma), mentioned above? We now have two equations that equal ‘F’; this means we can equate them, so:
Since F = ma and F = mg this means ma = mg
We see that the masses cancel out, so we have a = g, which is an interesting result. This means that when an object is in free-fall, its acceleration does not depend on the mass of the object, and that the acceleration is only due to gravity.
Suppose we could remove all air resistance, i.e. produce a vacuum (which would do the trick). What would we expect if we drop a very heavy object (bowling ball) and a very light object (feather) at the same time, in a vacuum?
If our calculations are correct they should fall at the same time since the object’s masses don’t matter in free-fall, right?
Play this video and skip to 2:50 to see for yourself.
If you have any questions, leave them below and until next time, take care.