Hey guys, have a few questions I was hoping you guys could help me out with.(adsbygoogle = window.adsbygoogle || []).push({});

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4.13)******* One strategy in a snowball fight is to throw a snowball at a high angle over level ground. While your opponent is watching the first one, a second snowball is thrown at a low angle timed to arrive before or at the same time as the first one. Assume both snowballs are thrown at an angle of 70.0 degrees with respect to the horizontal. (a) at what angle should the second snowball be thrown to arrive at the same point as the first? (b) How many seconds later should the second snowball be thrown after the first to arrive at the same time?

What I did:

First I drew a digram and made a line represting the resultant (r) vector which is 25.00 m/s. I knew my angle, which is 70 degrees. from this, I'm able to use one of 4 formulas to find the components of r which = 25 degrees.

for velocity:

Vxi = (vi)(Cos)(angle)

Vyi = (vi)(Sin)(Angle) - gt

for displacement:

x = (vi)(Cos)(angle)(t)

y = (vi)(Sin)(angle)(t) - 1/2(g)t^2

so I solved the initial velocity for the x components, which was:

vxi=(25)(Cos)(70) = 8.5 m/s

and the y component

vyi= (25)(sin)(70) = 23.49 m/s

at this point, I tried a formula for the x component for displacement, and got:

8.5t

but I figured I could find time by using the y component seeing as how I know the snowball will be at 0 velocity at the max height. So I could use the kinematic equation vf = vi+at . so if I plug that in I get:

0 = 23.46 + (-9.8)t

-23.46/-9.8 = 2.3969 s

and I would have to x2 so that it covers the whole distance so the t = 4.793 s

now, if I plug that into the equation 8.5t , I would get :

8.5 (4.793) = 40.7405m

So now I know my displacement of snowball 1 (and I'm assuming for snowball 2)

Now at this point I'm stuck. I don't know what to do with the information I have to get the missing angle for snowball 2 and have no idea how to calculate what I need to launch snowball 2 for it to = the time for snowball one. Can anyone help?

I also had a comment about how the first question didn't make sense. I double-checked the question and it was exactly the way I stated above. I'm also going to do 3 posts as someone said it was confusing having all 3 in one post. Thanks

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# Homework Help: Snowball fight angle Question

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