[mz simmonz]

OK this one problem is driving me and my friend nuts. We plugged in our numbers according to the formula in the textbook AND workbook and we still got it wrong Please can anyonee help me with this?

A cannon sends a projectile towards a target a distance 1280 miles away. The initial velocity makes an angle 33degrees with the horizontal. The acceleration of gravity is 9.8 m/s2. I already solved for the magnitude of the initial velocity which is 117.18 m/s. Now I'm TOTALLY STUCK for the 2nd part

*How high is the highest point of the trajectory? Answer in units of (m).

I'm gonna continue trying to work this out but I got it wrong 3 times already!

[becauseisayso]

Okay. i'm going to solve this step by step

1. If the distance is 1280 miles, that would mean if you convert it to meters, it is 1280 X 12 in X 2.54 cm X 5280 ft X 1 m divided 100 cm... ok if you dont get that. dimensional analysis and it should be correct.

1280 miles is equal to 2059960.32 meters

Are you giving me the right magnitudes here? Miles? or a typo?

2. if it makes an angle of 33 degrees. THERE IS NO way you can just solve for the initial velocity. there has to be another information given. Normally some sort of velocity is given...but in your case, i'll just take in account that your 117.18 meters per second is correct.

if that's the initial that would mean, the the vertical velocity would be 63.83 meters per second

3. 2059960.32 divided by 2 = 1029980.16 meters
the highest point would be perpendicular to this distance on the ground. (this is extra information so you can visualize where the highest point would be... which is half of a parabola)

so. you solve for it by

-(63.83)^2 = 2(-9.8)d
4074.2689 / 19.6 = d
207.87 meters is the distance of how high the cannon is..

THIS SHOULD BE CORRECT..

IF and ONLY IF

what youre INITIAL VELOCITY, 117.18 given is CORRECT.
Secondly, if 1280 MILES is correct as well.

Anyway, hope it is right.






By the way, what course would this be? Regular college physics? High school physics (ie, AP physics, regular physics) I'm curious :] Thanks