Question

An iron ball and a wooden ball are released from a height in vacuum. The speed of the iron ball would be:
A. Same to the speed of the wooden ball
B. More than the speed of the wooden ball
C. Lesser than the speed of the wooden ball
D. None

Answer 1

Iron balls are made up of iron. The mass of the iron is comparatively higher than that of the wooden ball. The wooden ball is made up of wooden material. The density of the iron ball is higher than the wooden ball.

Complete answer:
When the ball is released from the height. The ball gets attracted towards the centre of the Earth. The force exerted on the ball is the force of gravity. The gravitational force is always attractive in nature. So, when the object is at the height from the Earth surface. It always gets attracted towards the Earth.
The speed of the ball falling on the Earth is given as:
$\Rightarrow v=\sqrt{gh}$
Where, g is the acceleration due to gravity and h is the height of the ball.
The speed of the iron ball is given as:
$\Rightarrow {{v}_{1}}=\sqrt{gh}$
The speed of the wooden ball is given as:
$\Rightarrow {{v}_{2}}=\sqrt{gh}$
So, the speed of the ball is independent of the mass of the ball.
Therefore,
$\Rightarrow {{v}_{1}}={{v}_{2}}$

Option A is correct.

Note:
Another method:
The ball at height has kinetic energy zero. The potential energy of the ball is maximum at height h. So, the potential energy of the ball gets converted into the kinetic energy.
Potential energy = Kinetic energy
$mgh=\dfrac{1}{2}mv^{2}$
The speed of the ball falling on the Earth is given as:
$v = \sqrt{2gh}$
The speed is independent of the mass of the ball.