# Acceleration question -- Deceleration of a baseball being caught by a player

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1. Feb 18, 2015

### Rasofia

1. A baseball is travelling at +18 m/s and is caught by a player. The ball is brought to rest in 0.5 s. What is the acceleration of the ball?

2. Relevant equations
Maybe vf=vi+ at ?

3. The attempt at a solution
This is under a Horizontal Projectiles worksheet by the way...I'm not sure what to do on this one though. At first I thought to use the equation above and make 18 the final velocity since that's how it's caught...but then what would be the initial? So then I thought...okay maybe the initial could be 18 and the final is 0 since it says 'at rest'. I don't know, this is a bit complicated. Well, If I do it the second way, I get 36 m/s^2

Last edited by a moderator: Feb 19, 2015
2. Feb 18, 2015

### SteamKing

Staff Emeritus
When you catch a ball in a glove, how fast is it going when it comes to rest?

Is the catcher flung backwards by the ball he has caught?

When you are at rest on your couch, do you have any velocity?

This problem is complicated only because you are over thinking it.

3. Feb 18, 2015

### Rasofia

so I'm right, it's 36?

4. Feb 18, 2015

### SteamKing

Staff Emeritus
It appears to be so.

5. Feb 19, 2015

### haruspex

Not quite. The initial speed is carefully stated as "+18m/s". If you plug that in as vi in your "relevant equation" and put vf=0, what exactly do you get for a?