Calculating Angle C in Vertical Plane: Trigonometric Problem in Dynamics Book

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The discussion focuses on calculating the ascention angle C in a trigonometric problem involving an airplane tracked by radar stations A and B. Given the angles A (30 degrees) and B (22 degrees), along with angular speeds of A (0.026 rad/s) and B (0.032 rad/s), participants provided a structured approach to derive angle C. Key steps include determining the lengths of AC and BC using the height y, decomposing the velocity vector, and applying the relationship between angular velocity and the vectors involved. The problem is effectively solved by utilizing vector decomposition and angular relationships.

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Pyrrhus
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Hello, I'm in need of a hint or few pointers on how to calculate the angle C of the picture attached. I've already calculated y.

I was doing a few problems in this Dynamics book, i bought recently, and the ascention angle (angle C) is beating me :eek:

"The airplane C is being tracked down by the radar stations A and B. At the instant shown on the picture, the triangle ABC encounters itself in vertical plane and the lectures are Angle A = 30 degrees, Angle B = 22 degrees, Angular Speed A = 0.026 rad/s, Angular Speed B = 0.032 rad/s. Find a) the height y, b) the magnitude of the velocity (the vector V is at point C directed at an ascention angle (angle C) with respect tot he horizontal c) the ascention angle at the instant shown (angle c)"

ah yes distance d = 1000 m and it's between the stations A and B.

I hope the diagram is clear enough...
 

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A few hints:
1) Having "y", it is easy determine lengths of AC, BC, and form the vector from A to C, and the vector from B to C.
Let for example the vector from AC have the form \vec{r}_{AC}=r_{AC}\hat{r}_{AC}
where r_{AC},\hat{r}_{AC} are the length and direction vector, respectively.

2) Let \hat{n}_{AC} be the unit vector in the plane of the triangle perpendicular to \hat{r}_{AC} and pointing in the direction of increasing angle, and make a similar construction for \hat{n}_{BC}

3) Decompose your velocity as:
\vec{v}=v_{AC}\hat{r}_{AC}+v_{BC}\hat{r}_{BC}

4) We therefore have, for example the equality:
\vec{v}\cdot\hat{n}_{AC}=r_{AC}\omega_{AC}\to{v}_{BC}\hat{r}_{BC}\cdot\hat{n}_{AC}}=r_{AC}\omega_{AC}\to{v}_{BC}=\frac{r_{AC}\omega_{AC}}{\hat{r}_{BC}\cdot\hat{n}_{AC}}
where \omega_{AC} is the angular velocity measured at A.

5) Thus, we have determined \vec{v} and may answer the two remaining questions.
Remember that \hat{r}_{AC},\hat{r}_{BC} are not orthogonal vectors!
 
Last edited:
Thanks Arildno, i was able to solve it. :biggrin:
 

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