# Projectile magnitude and angle question

Hello, I am currently taking AP physics and require some assistance with a problem. I have to find the magnitude and angle of the original velocity of a projectile, normally this would be no problem for me but the original height is not zero which is giving me some problems.

My givens are:
t= 4.5s
dx= 45m
h= 1.6m

I believe I can get the x component with:
delta x=vox t +1/2gt**2
45m=vox(4.5s) + 4.905(4.5s**2)
so vox= .4334

If I did the above correctly all I would need now would be the y component, the problem is I have no idea on how to find it.

Any assistance would be greatly appreciated.

Related Introductory Physics Homework Help News on Phys.org
Please post the exact question as it appears in your book. Your method of finding the x velocity is wrong. Think, what direction is the acceleration?

The problem is:
A football player punts the football so that it will have a "hang time" (time of flight) of 4.5 s and land 48 m away. If the ball leaves the player's foot 160 cm above the ground, what initial velocity must the ball have?

Also, yes I did do teh x component wrong. I think it should be:
delta x=vxt + xo
48=vx4.5 + 0
so vx= 10.66

VietDao29
Homework Helper
Yup, you got the correct x-component. v_x = 10.66 m / s.
Now your goal is to find the initial y-component.
First, you know that the ball has a 'hang time' of 4.5 s, and it's 1.6 m above the ground. What equation should you use to find out the initial velocity with the given information?
Note that the ball has an acceleration of -g (downward).
So you can use:
$$x = x_0 + v_it + \frac{1}{2}at ^ 2$$
to find v_i (the initial y-component).
x_0 is the ball's initial position (or height), ie: 1.6 m.
When the ball hits the ground, x = 0.
With the x-component and the y-component, can you find out the ball's initial velocity?
Viet Dao,

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