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The height in meters of a projectile can be modeled by h = −4.9t2 + vt + s where t is the time (in seconds) the object has been in the air, v is the initial velocity (in meters per seconds) and s is the initial height (in meters). A soccer ball is kicked upward from the ground and flies through the air with an initial vertical velocity of 4.9 meters per second. After how many seconds does it land approximately?
 one year ago
 one year ago
The height in meters of a projectile can be modeled by h = −4.9t2 + vt + s where t is the time (in seconds) the object has been in the air, v is the initial velocity (in meters per seconds) and s is the initial height (in meters). A soccer ball is kicked upward from the ground and flies through the air with an initial vertical velocity of 4.9 meters per second. After how many seconds does it land approximately?
 one year ago
 one year ago

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KiArUnsYuBest ResponseYou've already chosen the best response.0
you just confused me.
 one year ago

onmng314Best ResponseYou've already chosen the best response.3
My bad. Are you familiar with calculus, namely derivatives?
 one year ago

onmng314Best ResponseYou've already chosen the best response.3
OK. No problem. I can help you solve it using another method. Stand by
 one year ago

satellite73Best ResponseYou've already chosen the best response.0
\[4.9t^2+49t=0\]solve for \(t\)
 one year ago

onmng314Best ResponseYou've already chosen the best response.3
h = −4.9t2 + vt + s First let's try to understand this formula and what it means. h is telling you how high the projectile is at ANY point in time. 4.9t^2 is telling you that gravity is acting downward. vt is allowing you to specify the initial velocity (they gave you this information, namely 4.9 meters per second). s is telling you where the projectile is starting (they also told you this, namely at the ground or ZERO). How are you doing so far?
 one year ago

onmng314Best ResponseYou've already chosen the best response.3
satellite73 gave you the short and sweet version. Let me know if you know how to solve a quadratic.
 one year ago

onmng314Best ResponseYou've already chosen the best response.3
Satellite also gave you the wrong formula. He wrote 49t. That means the ball is moving initially at 49 meters per second. Is that what the problem gave you?
 one year ago

onmng314Best ResponseYou've already chosen the best response.3
t=0 is a correct solution. That is telling you that the ball was at a height of ZERO, the clock started. Your second solution is the answer you need.
 one year ago

onmng314Best ResponseYou've already chosen the best response.3
Solve 0=4.9t^2+4.9t You should get t=0 t=.9574 (not rounded)
 one year ago
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