How Accurate Are These Projectile Motion Calculations?

[Nubcake]

I have a few questions about projectiles that I just want to verify that my calculations and working out is correct.

A bullet is fired horizontally from a rifle at 250 m s -1. after traveling 100m the bullet strikes a target

Calculate the time take for the bullet to strike the target
Calculate the downward component of velocity of the bullet when it strikes the target



S= ut



For the first one I did
100 = 250t
t =0.4 s

And the second
Since the initial vertical velocity is 0
u = 0
t = 0.4
a = 9.8

v = u + at
v = 0 + 9.8 x 0.4
v = 3.92 m s -1


Another question is

Simultaneously a ball is thrown horizontally from a height and another is dropped from rest at the same height , which ball hits the ground first?

My answer.

Both balls hit the ground at the same time since the initial vertical velocity of both balls is 0 they both free fall with the same acceleration.


Are these answers right because I do not have the answers to them

 

[Doc Al]

Looks good to me.