This is a very good question and I got the same answer as your teacher :eagerness:
The first thing I should do is drawing the diagram to see the actual picture of the problem
Next, since this is Projectile Motion problem, this problem require 2 components, x and y
Now, no the given, so you can choose which equation to choose. For this, we choose the following equation [TABLE="class: maths"]
[TR]
[TD="align: right"]x = [/TD]
[TD="align: left"]x0 + v0Δt + ½aΔt2 [/TD]
[/TR]
[/TABLE]
Now, set the two components for x and y
y-component:
Yf - Yi = V(iy) t + 12 ayt2 You know the origin is where the ball is hit which makes yf=0 and yi which stand for y final equal to -2.4m. v initial is zero because the ball is throwing side away so imagine like dropping the ball. The acceleration is 9.8. Now sub it in, you get the amount of time that it takes to hit the ground.
x-component:
v initial is 30m/s
acceleration is 0 since the direction is going side way
just plug it in to the x component. After you have the equation set up, plug in the t which give you the answer for B. The distance that it hits the ground
For part A
just use 12m away, so you want to know when the ball flies pass at 12m.
Simple, use the x component equation. make x-xinitial=12m. Now you have the time which is 0.4second
The last step is plug into y component to find how high was the ball almost reach to the ground which is 0.784m
Now you can get the answer by simply take 2.4m-0.784m=20.7m
I hope this help, if you have trouble doing this, should check out more videos tutorials :star: