July 23, 2014

Homework Help: Physics

Posted by Physics on Friday, September 18, 2009 at 9:18pm.

I gues I'm looking at this the wrong way i do not understand the work you do to get to the answer


Find the air velocity of a plane that must have a realtive ground velocity of 250.0 h^-1 km norht if it encounters a wind pushing it toward the northeast at 75 h^-1 km

The Work:

I do not follow it one bit...

Va = Vg - Vw
= 250 h^-1 km north - 75.0 h^-1 km northeast
= 250.0 h^-1 km north + 75.0 h^-1 km southwest
Va^2 = Vg^2 + Vw^2 - 2VgVw cos A
= (250.0 h^-1 km)^2 + (75.0 h^-1 km)^2 - 2(250.0 h^-1 km)(75.0 h^-1 km)(cos 45.0)
= 62 500 h^-2 km^2 + 5 625 h^-2 km^2 + 26 516 h^-2 km62
= 41 609 h^-2 km^2
Va = 204 h^-1 km
Vw/sin W = Va sin A
sin W = Vw sin A/Va
= (75 h^-1 km)(sin 45.0)/(204 h^-1 km)
= (75 h^-1 km)(.707)/(204 h^-1 km)
= 0.260
B = 15.1
Answer = 204 h^-1 km, 15.1 degrees west of north

ok i was lost on line 2 and three were the added and subtracted 75 with two different directions why are there two

line 3 were did this come from

- 2VgVw cos A


Answer this Question

First Name:
School Subject:

Related Questions

Physics - 1)The velocity of sound in air is 332 m/s. If the unit of length is km...
Physics - A golf ball is hit into the air, but not straight up, and encounters ...
Physics - I'd like to know when it is appropriate to use each formula. Im new to...
Calculus - average velocity - *VELOCITY OF A CAR* Suppose the distance s (in ...
Physics (please help!!!!) - A skydiver is subject to two forces: gravity and air...
PHYSICS-stuck - These are the troublesome questions. What is the average ...
Physics - At car (1140-kg)traveling at 24.8 m/s and truck (12600-kg) have a ...
Physics - A person takes in a breath of 13*C of air and holds it until it warms ...
toxicology- can someone re work this question? - Hi, I have to answer this ...
physics - The question has three parts, it looks like a lot but it is just ...