# Projectile motion of a baseball

1. Nov 16, 2007

### unknown_2

hey, i'm having some difficulty with this problem.
Code (Text):

/
/                                                            |
[U]/ ) 45     [/U]                                                   |
|                                                         | 3.0m
| 1.3m                                                    |
|[U]                                                         |             [/U]
130m

this is pritty much what i have. i have no clue where to start. i've been trying to figure it out but no success... :(

2. Nov 17, 2007

### Shooting Star

3. Nov 18, 2007

### unknown_2

uh...i did...i did lyk..30 questions on projectile motion...i know how to do the questions. i'm just stuck on this question.

Last edited by a moderator: Nov 23, 2007
4. Nov 18, 2007

### Faloren

Were you not given a value for time between the ball being hit and it clearing the wall?

(Although you may not need it for this question)

5. Nov 18, 2007

### akatz

ok...i am pretty sure i can help you witht his one :)
if you have been learning projectile motion in class then you should know:
$$\Delta Y = (V_{0}sin\varphi)(t)-.5gt^{2}$$
where $$\varphi = 45 degrees (the angle of "launch"$$
also you should know:
$$\Delta X = (V_{0}cos\varphi)(t)$$

NOW here is what you will have to do:
solve the change in X function for t and plug that in for wherever "t" appears in the change in Y equation
set the change in Y to equal 1.7 m (the ball needs to at least hit that point to make it over the wall) and then solve that big nasty equation algebraically to get $$\ (V_{0}$$

***edit : sorry its my first time with the math code so ill write this out
phi = 45 cuz its the angle of launch (the writing was kinda hard to read)