(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A knight fires a cannon ball from the top of the castle wall. the cannonball is fired at a speed of 55 m/s and an angle of 27 degrees above horizontal. A cannon ball is accidentally dropped and hits the moat below in 1.4s.

how far from the wall does the cannon ball hit the ground?

2. Relevant equations

any of the kinematics.

3. The attempt at a solution

so i have figured by adapting a kinematic equation that the height of the wall is 9.61184 m tall. Y_{o}= 1/2 a_{y}(change in t)^{2}

i have placed my coordinates at the base of the wall.

X_{o}= 0

X= ???

V_{ox}= 55cos27

V_{x}= 0

a_{ox}=0

a_{x}= 0

t_{o}= 0

t = i believe this would be 3.9458 seconds, but i may be incorrect...

Y_{o}=9.61184 ( calculated by gravity acting on the ball that was dropped)

Y=0

V_{oy}=55sin27

V_{y}=0

a_{oy}= -g

a_{y}= -g

t_{o}= 0

t = i believe this would be 3.9458 seconds, but i may be incorrect...

i know that my initial V in the x direction is 55cos27 and initial V in the y direction is 55sin27.

now i have tried solving first for the time it takes for the ball to hit the ground in the Y direction. this is where i have trouble. i cant seem to isolate my change in time in any kinematic equation.

i would assume once i have the change in time in the Y direction, i can then use that value to determine the final resting position in the X plane.....

more or less i need help just understanding how to go about this problem in an organized systematic way.... any help at all would be greatly appreciated..

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# Homework Help: Projectile Motion cannonball fired on top of a wall.

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