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?

Answer 1

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.