# Projectile Motion Bullet Shot Help

1. Nov 25, 2013

### yogoes123

1. The problem statement, all variables and given/known data

bullet shot horizontally over level ground with a velocity of 300m/s. at the instant that the bullet leaves the barrel, its empty shell casing falls vertically and strikes the ground with a vertical velocity of 5.00m/s

how far does the bullet travel

what is the vertical component of the bullet's velocity at the instant before it his the ground?

I tried a bunch of stuff and I didnt get the right answer, can someone just point me in the right direction? Please, at least tell me which equation to use cause I cant figure this out.

Last edited: Nov 25, 2013
2. Nov 25, 2013

### Staff: Mentor

Hi yogoes123. Is there a question attached to this statement?

3. Nov 25, 2013

### yogoes123

sorry i somehow missed that, very sorry i edited it.

4. Nov 25, 2013

### Staff: Mentor

Same here. I can't figure out which equation to use until I have condensed that wordy statement into something that looks more mathematical.

First thing, write down all the information that you know, expressing it as values of variables, e.g.,

bullet: vi = 300 m/sec

casing: vi = ???
vf = ???

etc.

5. Nov 26, 2013

### rude man

what is distance d of fall given time of fall T?
what is velocity of fall, given time of fall T?

6. Nov 26, 2013

### yogoes123

Ok guys i think there is a bit of confusion. The question says the bullet has a horizontal velocity of 300 m/s.

They want you to find range.

They also say the bullet shell falls vertically at a rate of 5 m/s, not sure why but its probably needed.

Thats all they give u.

Horizontal Velocity of bullet: 300 m/s

Vertical velocity of SHELL: 5m/s

7. Nov 26, 2013

### rude man

You need to quote the actual problem verbatim for us. The casing will not fall with uniform velocity.

8. Nov 26, 2013

### yogoes123

A sharpshooter shoots a bullet horizontally over level ground with a velocity of 3.00 x 10^2 m/s. At the instant that the bullet leaves the barrel, its empty shell casing falls vertically and strikes the ground with a vertical velocity of 5.00 m/s

a) How far does the bullet travel

b) What is the vertical component of the bullet's velocity at the instant before it hits the ground.

9. Nov 26, 2013

### arizona1379

Break this down into your knowns and unknowns.

You only have four kinematic equations.

This problem is a projectile problem that is asking you to break things up in terms of x and y. First the shell moves initially with the bullet at 300 m/s horizontally, and then when it approaches 0 m/s, due to gravity it accelerates vertically at 9.8 m/s2 towards the earth to reach a final velocity of 5 m/s.

So what do you know?

Horizontal Movement

Vix= 300 m/s
t=(5m/s)/(9.8m/s2)=0.5097s
ax= 0 m/s2
Δx=?

Δx=(vix)(t) + (0.5)(ax)(t)2

Vertical Movement

viy= 0 m/s
vfy= 5m/s
ay= 9.8 m/s2
Δx=?

vfy2 = viy2 + (2)(ay)(Δy)

Last edited: Nov 26, 2013
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