# Projectile Motion velocity homework

## Homework Statement

A projectile is fired horizontally from a gun that is 55.0 m above flat ground, emerging from the gun with a speed of 350 m/s.
a) How long does the projectile remain in the air?
b) At what horizontal distance from the firing point does it strike the ground?
c) What is the y-component of the velocity as it strikes the ground?
d) What is the magnitude of its speed as it strikes the ground?
e) At what angle does the projectile strike the ground?

## Homework Equations

V1x=V1cosθ
V2x=V1cosθ
x=(V1cosθ)t
V1y=V1sinθ
V2y=(V1ysinθ)t-gt
y=(V1sinθ)t-0.5gt^2

## The Attempt at a Solution

So I attempted each one and just want feed back on my answers.
a)t=3.4s
b)x=1190m
c)-33.32m/s
d)351.6m/s
e)355 degrees

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1. The precision of the time result is rather low, so some of the significant digits in the subsequent results are incorrect.

2. 355 degrees cannot be an angle with which the projectile strikes the ground, because this is underground. The angle must be less than 90 degrees.

So the timing is incorrect?
This is what I did....
y=(350m/sin(0))t-0.5gt^2
-55m=-0.5(9.8m/s^2)t^2
-55m/-4.9m/s^2=t^2
t=3.35s so I rounded it to 3.4s

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1. The precision of the time result is rather low, so some of the significant digits in the subsequent results are incorrect.

2. 355 degrees cannot be an angle with which the projectile strikes the ground, because this is underground. The angle must be less than 90 degrees.
Not necessarily.

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