SOLUTION: use the formula h = rt - 4.9t2 a projectile is fired upward with an initial speed of 2940 m/s. After how many minutes does it hit the ground? how do we figure this out? w

Algebra ->  Real-numbers -> SOLUTION: use the formula h = rt - 4.9t2 a projectile is fired upward with an initial speed of 2940 m/s. After how many minutes does it hit the ground? how do we figure this out? w      Log On


   

Question 126872This question is from textbook algebra 1
: use the formula h = rt - 4.9t2
a projectile is fired upward with an initial speed of 2940 m/s. After how many minutes does it hit the ground?

how do we figure this out? we are stuck! thanks This question is from textbook algebra 1

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
h%28t%29=rt+-+4.9t%5E2
I'm assuming that r is the initial speed in m%2Fs.
Also, I'm assuming that the units of 4.9 are m%2Fs%5E2.
That's your gravity terms (1/2 g).
h%28t%29=2940t+-+4.9t%5E2
At time t=0 seconds, the projectile is on the ground, about to be fired.
h%280%29=2940%280%29-4.9%280%29%5E2
h%280%29=0
You need to find the next time h(t)=0.
2940t-4.9t%5E2=0
2940-4.9t=0Divide both sides by (t).
2940=4.9tAdd (4.9t) to both sides
t=2940%2F4.9Divide both sides by (4.9).
t=600
In 600 seconds, the projectile will hit the ground.
600 seconds = 10 minutes.