AP Physics - 2D Projectile motion with rifle

[joycejoohee]

Homework Statement

A rifle is aimed horizontally at a target 100 ft. away. The bullet hits the target
0.75 in. below the aiming point. (a) Calculate the bullet’s time of flight. (b)
Calculate the muzzle velocity of the rifle. (g = 32 ft/s

Homework Equations

delta x = vx * t
delta y = 1/2at^2 + vi t

The Attempt at a Solution

100=vx*t
(two unknown variables?!)
-100=(-16t/s^2)(t^2) + vixt

 

[SteamKing]

You know how far the bullet drops from the time it leaves the rifle until it hits the target. Can't you find out how long for the bullet to drop this amount?