A ball is dropped from the top of an 80 m building.with what speed does the ball hit the ground?

Ping Pong Ball or Lead ball?

Ping Pong Ball or Lead ball?

Unless the ball is influenced disturbances in the process of falling through the air (resistance) then it doesn't really matter.

Yes. In this case there would be a great difference when it comes to comparing the acceleration rate of a ping pong ball and a lead ball.

Leaving this objection aside for the moment I assume that the O.P. is after
gravitational acceleration ,or 9.8 meters per second squared. The displacement is -80 meters because the object is falling.

Assuming the ball is dropped, not thrown from a height of 80 meters they can infer 0 meters per second squared at the start.

The thing they don't know is the time taken for the ball to reach the bottom. Using the correct kinematic equation will solve the problem.


Tut

Also, do you remember the experiment of Galileo Galilei when he was at the top of the tower of Piza? :)

Yes, I think it was a 1 pound weight and a 10 pound weight, and could see how they fall at the same speed. I personally think a lead ball will hit the ground Noticeably sooner than a ping pong ball. However, Like Aristotle, I am basing on current beliefs, no actual experiment to confirm.
Any Bets?

As Tut said, the ping pong ball will be subject to air resistance. When you apply air resistance, it's the weight and the area which determines the net force with which the ball is being pulled down.

Now, let's say both balls have the same area in contact with air. The net force depends solely on the weight as follows:

F_{net} = W - F_{air}

Since the weight W of the ping pong ball is much lower, you can get F_net = 0 (meaning the ball will fall at constant speed, perhaps at say 5 m/s) while the steel ball might get a net force which causes it to accelerate constantly and always speeding up while falling.

Of course, there are other factors to make it more precise, but I don't think that they will help you understand the basics of that problem right now, but more confuse you to a certain point :)

A ball is dropped from the top of a 72m building. With what speed does the ball hit the ground?

There are kinematics formulae that will give you the answer. What are the formulae that you know about?