Answer:
A. 3.78 s
Explanation:
To know how long it will take to hit the ground, we need to use the following equation
[tex]y=y_0+v_{oy}t+\frac{1}{2}at^2[/tex]
Where y is the final height, so y = 0 m
y0 is the initial height, so y0 = 70 m
voy is the initial vertical velocity, so it is voy = 0 m/s
t is the time
a is the acceleration due to gravity, so a = -9.8 m/s²
Now, we can replace the values and solve for t, so
[tex]\begin{gathered} 0=70+0t+\frac{1}{2}(-9.8)t^2 \\ \\ 0=70-4.9t^2 \\ \\ -70=-4.9t^2 \\ \\ \frac{-70}{-4.9}=t^2 \\ \\ 14.29=t^2 \\ \\ \sqrt{14.29}=t \\ \\ 3.78\text{ s = t} \end{gathered}[/tex]
Therefore, the answer is 3.78 s
