Lucku H.
asked 11/11/15Physics-trig question velocity of a plane etc HELP
A plane flies due north (90° from east) w/ a velocity of 110 km/h for 3 hours.A steady wind blows southeast at 35 km/h at an angle of 320 degrees from due east during this time. After 3 hours, where will the plane’s position be relative to its starting point?
I`m having trouble getting the answer I`ve started off with the formula v=sqrt{v(p)²+v(w)²-2v(p)v(w)cos α}
=sqrt(110²+35²-2*110*35cos45) = 88.8 km/h (rounded) Then did
s= vt=88.8*3=266.4 km
then tried getting the distance from the start by the following:
sqrt.(266.4^2 + 88. = 266.6 km N.E from starting point.
Although I have no idea why (trying to imitate a similar problem I did
this to get the angle from the start using tanL , L being the length
tanL = (266.6/88., which equals about degrees
Please explain . Agh thank you soo much
I`m having trouble getting the answer I`ve started off with the formula v=sqrt{v(p)²+v(w)²-2v(p)v(w)cos α}
=sqrt(110²+35²-2*110*35cos45) = 88.8 km/h (rounded) Then did
s= vt=88.8*3=266.4 km
then tried getting the distance from the start by the following:
sqrt.(266.4^2 + 88. = 266.6 km N.E from starting point.
Although I have no idea why (trying to imitate a similar problem I did
this to get the angle from the start using tanL , L being the length
tanL = (266.6/88., which equals about degrees
Please explain . Agh thank you soo much
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1 Expert Answer
It is easy to use component vectors when solving problems of this type.
Velocity of plane = 0 i + 110 j
Velocity of wind = 35 cos 40 i - 35 sin 40 j = 26.81 i - 22.50 j
The resultant velocity is the sum of these two vectors = 26.81 i + 87.5 j
The plane's position after 3 hours is 3 x (26.81 i + 87.5 j) =
Find the magnitude of this position vector by using the Pythagorean Theorem.
The direction of the vector is the Tan ^-1 (87.50/26.81).
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Mark M.
11/11/15