Question

1.

Answer 1

Answer:

The rock will be be 5  meters from ground level at time = 3.713 seconds

Step-by-step explanation:

As we know-

$s(t) = -4.9 * t^2 + v_0t + s_0$

V0 = velocity

S0 = height above ground when thrown

Substituting the given values, we get -  

$9 = -4.9* t^2 + 12 * t +32\\-4.9*t^2 +12*t + 23 = 0$

As per the formula

$t = \frac{-12+ \sqrt{12^2 -4*(-4.9)*23} }{(2*(-4.9)} \\t = 3.713$

The rock will be be 5  meters from ground level at time = 3.713 seconds