Question

Which of the following variables would you need in order to calculate how long it would take a horizontally launched projectile to hit the ground?

Answer 1

To calculate how long it would take a horizontally launched projectile to hit the ground we will need to know only the height of the projectile. The correct option is 4.

To calculate how long it would take a horizontally launched projectile to hit the ground (the time of flight), we need to use the following equation:  

$y_{f} = y_{i} + v_{i_{y}}t - \frac{1}{2}gt^{2}$   (1)

Where:                

t: is the time      

$y_{f}$: is the final height = 0 (when it hits the ground)

$y_{i}$: is the initial height

$v_{i_{y}}$: is the initial vertical speed of the projectile = 0

g: is the acceleration due to gravity = 9.81 m/s²

Hence, by solving equation (1) for t:

$t = \sqrt{\frac{2y_{i}}{g}}$  

Hence, we will need only to know the height of the projectile to find the time. The correct option is 4.

You can see another example of projectile motion here: https://brainly.com/question/10903823?referrer=searchResults                                      

I hope it helps you!