(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A soccer ball is kicked with an inital speed of 12.0 m/s in a direction of 25.0 degrees above the horizontal. Find the magnitude and direction of its velocity A) 0.250 s and b) 0.500 s after being kicked. C) Is the ball at its greatest height before or after 0.500 s?

2. Relevant equations

a = (V_{f}- V_{i})/t

d = ((V_{i}+ V_{f}f / 2)t

d = V_{i}t + 0.5at[super]2[/super]

V_{f}= 2ad + V_{i}[super]2[/super]

3. The attempt at a solution

I'm really stuck on this.

I've gone with:

Vh = cos(25)12.0m/s

Vh = 10.88 m/s

Vi = sin(25)12.0m/s

Vi = 5.07 m/s

Now I've heard that in class if your initial vertical velocity in these types of problems has to be equal to the final or finishing vertical velocity...

So since I have Vi = 5.07 m/s ; I set Vf = -5.07 m/s

...and worked from there, but I am not sure at all if this was correct.

From there I tried to work out the displacement ...

Vf = 2ad + V_{i}[super]2[/super]

-5.07m/s = 2(-9.8m/s2)(d) + 5.07[super]2[/super]

d = 1.57 m

... and this is where I KNEW (at least I think I know...) that I'm horribly wrong. A kick with an initial vertical velocity of 5.07 m/s and overall 12.0 m/s ... and my displacement is 1.57 m total...

If anybody can help get me pointed in the right direction on this ... I would GREATLY appreciate it.

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# Homework Help: Basic Projectile: soccer ball kick

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