# Homework Help: Trig-type problem

1. Feb 19, 2008

### hi2u

Components / Vectors Problem

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

3. During the Civil War, Rear Admiral David Porter (a Boston
native) is ordered to steam his fleet of river-gunboats to
Vicksburg, Mississippi. He stops in the Yazoo River a distance d =
800 m from the town of Vicksburg, which is situated a height h =
76 m above the level of the river (see figure A). His gunboat
carries a cannon which can fire cannonballs with a velocity of v=
100 m/s. His objective is to destroy a bunker at the top of the
plateau.
[8 points] If the cannonball lands on the bunker when θ = 33.2o
, what is the height h of the plateau?

2. Relevant equations / Attempts

I tried drawing a triangle, tried using kinematics, where the upwards initial velocity was cos(33.2)*800, but that didn't work either. I know the correct answer is 76 (which is also ironically in the problem itself), but I'm not sure how to get to that. These are practice problems for a midterm tomorrow, so help is appreciated.

Thanks

Last edited: Feb 19, 2008