Question

HELP PLZ

Answer 1

Answer:

Explanation:

Use the equation

$h(t)=-16t^2+v_0t+h_0$

where h(t) is the height after a certain amount of time goes by, v0t is the initial upwards velocity, and h0 is the initial height of the projectile. For us:

h(t) = 10

v0t = 80

h0 = 3 and filling in:

$10=-16t^2+80t+3$ and get everything on one side to factor:

$0=-16t^2+80t-7$

This factors to

t = .09 sec and 4.9 sec. Let's interpret this.

The time of .09 is when the ball reached 10 feet on the way up, and

the time of 4.9 is when the ball reached 10 feet on the way back down. That's the height we need, 4.9 seconds.