Homework Help: physics

Posted by Nicole on Thursday, March 15, 2012 at 12:21pm.

You're on a magic bridge floating 25 meters above a lake. You through a rock at an angle of sixty degrees. It takes 5.8 seconds for the rock to reach it's highest point.

(a) With what speed did you throw the rock?
(b) How far away from the bridge horizontally did the rock land?

physics - bobpursley, Thursday, March 15, 2012 at 12:24pm
sixty degres measured how?
physics - Nicole, Thursday, March 15, 2012 at 12:29pm
Measured to the horizontal

Throw*
physics - bobpursley, Thursday, March 15, 2012 at 12:37pm
Then the vertical velocity initial is Vsin60.

At the top, vertical velocity is zero.

Vtop=Vivertial-gt
so time to top= Vivertial/g=Vsin60 /g
then solve for V

Now how far: You have to find vertical time in air.
hf=hi+Vivertical*t-1/2 g t^2
0=23+Vsin60* t-1/2 g t^2

solve for t, time in air. Use the quadratic formula.

Now distance: distance= Vhoriz*timeinair
where vhoriz= Vcos60

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