Question

When we drop an iron ball and a feather from a height, the iron ball reaches first. Why? But when we drop a wooden ball and an iron ball, they both touch the surface simultaneously. Why?

Answer 1

Dear Student

When we drop an iron ball and feather, the iron ball reaches first. That is because air resistance acts on the feather due to it's light weight and large surface as compared to iron ball.

In the second case,
Both the balls have same initial speed and same potential energy as finally the potential energy will change to kinetic energy finally.As the potential energy is same for both the balls they will have same final velocity.

According to the newton's law,
F = m a where, m= mass and a = acceleration
But, we know that F = m g , where g = acceleration due to gravity
Now equate both the equations of force we get,
m a = m g
it comes out a = g (in vacuum also g is acting)
Thus it does not depends on the mass, so different weights thrown from same height will reach the ground at the same time.

Regards