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A ball is thrown upward from the roof of a building 60m tall. The ball reaches a height of 80m above the ground after 2s and hits the ground 6s after being thrown.

a)sketch a graph that shows the height of the ball as a function of time (done) (0,60)to(6,0) 

b)state the domain and range D={xer|0<=x<=6} R={yer|0<=y<=80}

This one I dont get

c) Determine an equation for the function.

I used f(x)=a(x-2)2+80 but when I input a point the answer is never correct. 

 Oct 10, 2018
 #1
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You need to know the basic equation of ballistic motion

 

h(t)=gt22+v0t+h0

 

here they give you h0=60

 

they also seem to be using g=10 m/s2 which isn't quite accurate but close enough for government work.

 

You have two equations

 

h(2)=80, h(6)=0you really only need one of them, plugging in values we have80=5(22)+2v0+6020=2v020v0=20checking with the other equation we haveh(6)=5(62)+20(6)+60=180+120+60=0 as expected. So our equation of motion ish(t)=5t2+20t+60we can rewrite this ash(t)=5(t24t12)=5((t2)2412)=5(t2)2+80and this last is the standard form of the parabola 

 Oct 10, 2018

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