A rock is dropped from a bridge 320 feet above the river. The pathway that the rock takes can be modeled by the equation h= -16t2+320. How long will it take the rock to reach the river?
To find out how long it will take for the rock to reach the river, we need to find the time at which the height "h" is equal to 0 (since the rock will reach the river when its height is 0).
So, we set h = 0 in the equation h = -16t^2 + 320:
0 = -16t^2 + 320
Add 16t^2 to both sides:
16t^2 = 320
Divide both sides by 16:
t^2 = 20
Take the square root of both sides:
t = √20
t = 4.47 seconds
Therefore, it will take the rock approximately 4.47 seconds to reach the river.