# Homework Help: Projectile question - X and Y direction

1. Apr 5, 2012

### anthony123456

A bullet is fired at an angle of 60° with an initial velocity of 200 m/s. How long is the bullet in the air?

2. Relevant equations

Vix = Vicosθ
Viy = Visinθ

Vfy = Viy + ayΔt
Xf = xi + VixΔt

... Ask for more equations available....
3. The attempt at a solution

Vix = 200cos60° = 100m/s
Viy = 200sin60° = 173.2 m/s

X variables:
xi = 0m
xf = ?
Δt =?
Vix = 100m/s

Y variables:
Yi = ?
Yf = 0m
Δt =?
Viy = 173.2m/s
Vfy = ?
a = -9.8m/s

ANSWER HAS TO EQUAL 35.4 SECONDS, ACCORDING TO MY PHYSICS TEACHER!

2. Apr 5, 2012

### azizlwl

Relevant Equation
$Y=(V_{iy})t-\frac{1}{2}at^2$

3. Apr 5, 2012

### RoshanBBQ

The question is unanswerable, because you are not given knowledge about the initial y-component position of the bullet or the landscape into which the bullet will travel.

But if we assume your teacher meant to describe a world in which bullets are fired from ground level into landscapes that are perfectly flat, we can proceed. If that is the case, Yi = 0. If you need additional help, just ask for it.