When an object such as a feather is dropped from a height, the initial velocity is said to be $0$. I would assume that the final velocity would also be $0$ as when the feather reaches the ground, it stops moving. However, the final velocity is not $0$. Could anyone please answer why?
$\begingroup$
$\endgroup$
2
-
$\begingroup$ Who claims that the final velocity is not 0 and are you sure they don't mean the velocity right before the ground stops the object? $\endgroup$– ACuriousMind ♦Jun 14, 2020 at 14:23
-
$\begingroup$ If you use the third equation of motion, namely $v^2 = \ u^2 +\ 2as$, will you get your answer? $\endgroup$– Firefox1921Jun 14, 2020 at 14:58
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
Let's say the ground is at $x=1$ cm, imagine to move it below, at $x=0$ cm. What would be the velocity at $x=1$ cm? It is non zero.
You can think of the final velocity as the velocity the object has just before it hits the ground.
$\begingroup$
$\endgroup$
The feather has mass, and therefore if you will drop it from a certain height, it will accelerate (F = mg) and will surely gain velocity. ( Though, its velocity will become constant after some time when it attains terminal velocity, but it will not be equal to zero.
