Find the angle so that it seems that Mars is approaching to you

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Homework Help Overview

The discussion revolves around determining the angle at which Mars appears to approach an observer, involving concepts from kinematics and trigonometry. Participants are exploring the relationship between the velocities of Mars and the observer, as well as the geometric interpretation of these velocities.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the use of velocity vectors and trigonometric relationships to find the angle. There is a mention of using the sides of a triangle formed by the velocities to determine angles, prompting questions about the specific triangle being referenced.

Discussion Status

The conversation is active, with participants providing insights into the relationships between the velocities and the geometric interpretation. Some guidance has been offered regarding the proportionality of distances and velocities, but there is no explicit consensus on the approach to find the angle.

Contextual Notes

Participants are working under the assumption that the time until collision is fixed, which influences their reasoning about the proportionality of distances and velocities. There may be missing information regarding the specific triangle and its sides.

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Homework Statement
The spaceship S approaches Mars following the trajectory ##b−b## with velocity ##19.3 km/s## with respect to the Sun. If Mars has a velocity ##24.1 km/s## along the trajectory ##a−a## with respect to the Sun and the angle between ##b-b## and ##a-a## is ##30°## determine the angle between ##SM## and ##b−b## such that a person inside the spaceship "sees" that Mars is moving towards him
Relevant Equations
##v_{M/S}=v_M - v_S##.
I know that ##v_{M/S}=v_M - v_S##. I also know that ##v_M = (-24.1;0)##. Then, using some trigonometry, ##v_S=(-19.3 sin 30°;19.3 cos 30°)##.
So I can find ##v_{M/S}##. But that doesn't tell me anything about the angle ##\beta##.
 

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You have all three sides of a triangle, you can find the angles.
 
mfb said:
You have all three sides of a triangle, you can find the angles.
What triangle are you talking about? The one formed by the ##v_S##, ##v_M## and ##v_{M/S}##?
 
Yes. The time until you and Mars collide is fixed, so distances and velocities are proportional to each other.
 

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