# A question and no idea what to do

1. Sep 25, 2005

### ouse

determine the inital velocity of a projectile that is luncked horizantaly and falls 1.5m while moving 16m horizantaly
i tried everything all i figerd out is that they r displacmednts the accelaration is 9.8 and nothing i dont have enogh info to do anything
plz help me

2. Sep 25, 2005

### Päällikkö

Divide the motion into x and y components and deal with them as if you were dealing with one-dimensional motion.

3. Sep 25, 2005

### ouse

can u plz elaborate

4. Sep 25, 2005

### ouse

and any way that dosnt work becuse i have no angles to detrime wat the x and y componants are

5. Sep 25, 2005

### ouse

that would only work if these were vectors not displacment

6. Sep 25, 2005

### Päällikkö

Well...
$$x = v_0t$$
$$0 = y_0 -\frac{1}{2}gt^2$$
Does that help at all?

7. Sep 25, 2005

### ouse

yeah it helped i acctualy figerd the question thx sooo much

8. Sep 25, 2005

### ouse

now can u plz look at my other thread and plz ohh plz help with question 1 b,c and q 2

9. Sep 25, 2005

### Päällikkö

Did you understand where the equations I gave came from?

10. Sep 25, 2005

### ouse

ummm well yeah for one of them

11. Sep 25, 2005

### ouse

u assumed viy is 0 and took it our of the equation right

12. Sep 25, 2005

### Päällikkö

The full equations:
$$x = x_0 + v_{x0}t + \frac{1}{2}a_xt^2$$
$$y = y_0 + v_{y0}t + \frac{1}{2}a_yt^2$$
Let $x_0 = 0$. As the projectile's fired horizontally: $v_{y0} = 0$ thus $v_{x0} = v_0$. No force affects the projectile in x-direction, so: $a_x = 0$. In y-direction: $a_y = -g$ (- as it's downward). The final altitude of the projectile is $y = 0$.

Hence
$$x = v_0t$$
$$0 = y_0 -\frac{1}{2}gt^2$$

13. Sep 25, 2005

### ouse

i was woundring if u could help me with the other thread plz help me i really need it i have a test i need to pass

14. Sep 25, 2005

### ouse

thx for the explination