Question

A ball is dropped from rest from the top of a building of height h. At the same instant, a second ball is projected vertically upward from ground level, such that it has zero speed when it reaches the top of the building.
a. When do the two balls pass each other?
b. Which ball has greater speed when they are passing?
c. What is the height of the two balls when they are passing?

Answer 1

Answer:

Find the answer in the explanation

Explanation:

Given that a ball is dropped from rest from the top of a building of height h. At the same instant, a second ball is projected vertically upward from ground level, such that it has zero speed when it reaches the top of the building.

a. When do the two balls pass each other?

The the balls will pass each other before the second ball reach half of the height of the building. Because the velocity of the second ball decreases as it goes upwards while the velocity of the first ball increases as it moves downwards

b. Which ball has greater speed when they are passing?

The first ball of course because the velocity of the second ball decreases as it goes upwards while the velocity of the first ball increases as it moves downwards

c. What is the height of the two balls when they are passing?

Taking the height from the bottom of the building upward

Since the two balls meet at a certain point, they will both have the same height.