ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
AP Physics B 2.2 Newtonian Mechanics 174 Views
Share It!
Description:
AP® Physics B: Newtonian Mechanics Drill 2, Problem 2. If she is to stay on a course due north, at what angle must she point her plane?
Transcript
- 00:03
Shmoop, there it is... Shmoop, there it is...
- 00:07
Angry with the present she got for Christmas, Little Mary Sue
- 00:10
flies an airplane toward the North Pole in order to give Santa an earful.
- 00:14
Oh no, it's cool... she's got a pilot's license.
- 00:16
Mary Sue's plane flies at a speed of 100 meters per second,
Full Transcript
- 00:20
but there is a strong western-blowing wind of 35 meters per second.
- 00:25
If she is to stay on a course due north, at what angle must she point her plane?
- 00:30
And here are the possible answers...
- 00:39
Vectors! Problems!
- 00:40
With direction and magnitude, oh yeah! Whenever we have to deal w/ a problem with
- 00:45
vectors, we always, 100% of the time definitely for sure... draw a picture.
- 00:51
Mary Sue wants her v net to be north, but there is this pesky crosswind keeping her
- 00:56
from doing that easily. Instead, she has to fly diagonally into the
- 01:01
wind so that she can counteract the sideways movement.
- 01:06
V sub p is the flight path that she will take, and v sub w is the movement the plane will
- 01:12
have that is caused by the wind. When we add these two vectors together, we
- 01:16
want to get a north pointing vector... v sub net.
- 01:21
Now to plug in what we know. V sub p is equal to 100 meters per second,
- 01:25
and the wind, v sub w, is 35. That's... all we know.
- 01:29
But frankly, that's all we need to know. Because of the law of SOH CAH TOA,
- 01:38
we know that the cosine of an angle is equal to the adjacent side divided by the hypotenuse.
- 01:44
In this case, the cosine of theta is equal to v sub w divided by v sub p.
- 01:49
We want to find the angle of Mary Sue's plane, so to isolate theta, we take the arc-cosine
- 01:54
of both sides... to get arc-cosine of v sub w over v sub p.
- 02:01
Plugging in values of v sub p and v sub w, we get theta is equal to the arc-cosine of
- 02:06
35 over 100...
- 02:07
...or answer (A).
- 02:09
Give him a piece of your mind, Mary Sue.
- 02:11
St. Nick has to know who's in charge here.
Up Next
When you're about to marry the love of your life, not many things could stop you. However, finding out that your future hubby is keeping his crazy...
Related Videos
Here at Shmoop, we work for kids, not just the bottom line. Founded by David Siminoff and his wife Ellen Siminoff, Shmoop was originally conceived...
ACT Math: Elementary Algebra Drill 4, Problem 5. What is the solution to the problem shown?
AP® English Literature and Composition Passage Drill 1, Problem 1. Which literary device is used in lines 31 to 37?
AP® English Literature and Composition Passage Drill 2, Problem 1. What claim does Bacon make that contradicts the maxim "Whatsoever is delig...