Math - Horizontal Displacement Please help

Question

I have already answered 1 and 2. 3 is partially because I can't solve the horizontal displacement part.

1. A bullet traveling 508m/s horizontally hits a target 145 m away. How far does the bullet fall before it hits the target?
2. Alex throws a baseball 2.3 m/s horizontally from a height of 8 m. How far will the ball travel before it reaches the ground?
3. A ball is thrown from the top of a 45 m high building with a horizontal speed of 7.3 m/s. Calculate the time it takes to drop to the floor and its horizontal displacement at the point when it reaches the floor

Here is my answer for question 3 so far:

dx = 67.04081625m

t = 9.18367346

Answer 1

Hey Guinevere,

It looks like there might be a slight issue with what you've calculated so far. So this is a pretty common problem in physics which falls under a topic called kinematics or projectile motion.

We have our ball starting up 45 meters above the ground with an initial horizontal velocity, but (seemingly) no initial vertical velocity. To attack a problem like this, we have to separate it into vertical and horizontal components separately.

Vertically:

We know our starting position, and (without being told) we also know the acceleration due to gravity. So we should use d = v₀t + (1/2)at². From the answer you gave, it looks like you might've forgotten t is being squared here. Take a look over your work.

From there, we can attack the horizontal problem:

We now now how much time the ball was in the air, we know its initial velocity, and we assume no external forces act on the ball, so it isn't experiencing any horizontal acceleration. So really, you can use good ol' d=rt to solve the rest from here.

Hopefully that's enough of an explanation to get you there. Feel free to reach out if you have more questions!