Acceleration due to gravity of two objects

[omgitsmonica]

Homework Statement

Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street?

It's a multiple-choice question, and the choices are:

a. The one thrown up is traveling faster.
b. The one thrown down is traveling faster.
c. They are traveling at the same speed.
d. It is impossible to tell because the height of the building is not given.

Homework Equations

I don't know them, we're supposed to use logic.

The Attempt at a Solution

I think it should be a, because the one thrown up is gathering speed from the top of its arc and past the initial point. My study partner says c, because the ball going up cancels out the fall to the initial point.

Any suggestions?

 

[LowlyPion]

Homework Statement

Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street?

It's a multiple-choice question, and the choices are:

a. The one thrown up is traveling faster.
b. The one thrown down is traveling faster.
c. They are traveling at the same speed.
d. It is impossible to tell because the height of the building is not given.

Homework Equations

I don't know them, we're supposed to use logic.

The Attempt at a Solution

I think it should be a, because the one thrown up is gathering speed from the top of its arc and past the initial point. My study partner says c, because the ball going up cancels out the fall to the initial point.

Any suggestions?

Welcome to PF.

By symmetry you should understand in a uniform gravity field that the one thrown up at the same speed - roof level - will pass roof level at the same speed on the way down.

Do you want to change your answer?

 

[omgitsmonica]

Any suggestions?

Welcome to PF.

By symmetry you should understand in a uniform gravity field that the one thrown up at the same speed - roof level - will pass roof level at the same speed on the way down.

Do you want to change your answer?

Thanks.

So, if it passes the roof at the same speed it started at the roof, my study partner was right, because they both start at the roof at the same speed?

That means that they have the same speed when they hit the ground because of V=v_o+at, right?