Question

4. A bullet is fired horizontally from a 70 mtall building with a speed of 1400 m/s.How long will it take to hit the ground? (1 point)A. 03.78 SB. 06.558 SC. 07.162 sD. 05.059 sE. O 2.906 S

Answer 1

A. 3.78 s

Step-by-step explanation:

To know how long it will take to hit the ground, we need to use the following equation

`y=y_0+v_(oy)t+(1)/(2)at^2`

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

`\begin{gathered} 0=70+0t+(1)/(2)(-9.8)t^2 \\ \\ 0=70-4.9t^2 \\ \\ -70=-4.9t^2 \\ \\ (-70)/(-4.9)=t^2 \\ \\ 14.29=t^2 \\ \\ √(14.29)=t \\ \\ 3.78\text{ s = t} \end{gathered}`

Therefore, the answer is 3.78 s