# B The dropping of two identical balls without air resistance

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1. Nov 1, 2018

### M23

I was thinking about this and couldn't really figure it out.

You are standing on a cliff and you have two identical balls. In this case, air resistance is to be ignored. The only thing different is that you throw the ball horizontally at different speeds. Lets say you threw ball one at a speed of 5m/s and the other ball at 10m/s

Will the balls land at the same time? Will the balls have the same speed when they land?

My thinking:

Since air resistance is ignored, I know that the horizontal component will be constant throughout. However, I wasn't really sure how no air resistance will affect the behavior of the ball. Could someone please answer the two question above?

Thank you very much.

2. Nov 1, 2018

### CWatters

Some hints..

They have the same vertical velocity at the start.
They have the same vertical acceleration (g).
So will they have the same vertical velocity all the time?
[strike]Time = distance/velocity.[/strike]

Will they have the same vertical velocity?
Will they have the same horizontal velocity?
Do you know how to add vectors?

Last edited: Nov 2, 2018
3. Nov 1, 2018

### kuruman

Hi M23 and welcome to PF.

1. No air resistance means that the only force acting on the balls is gravity. In other words, their acceleration is g. What does this imply about the time of flight? You are on the right track.
2. If the balls don't have the same initial speed, why should their final speed be the same?

4. Nov 1, 2018

### kuruman

Only in the horizontal direction, of course.

5. Nov 2, 2018

### CWatters

Yes sorry not sure why I put that in there when talking about the vertical velocity.