Relative movement

[kenhung123]

There is a few questions that I encountered which asks what is the motion of an object relative to another/seen by someone at a particular position. I never really studied anything related to these perception of the motion of objects.. How do they work?

[/0]

Relative motion problems can be quite tricky to conceptualize, but there is really only one formula you need to know which gives you a methodical way to solve problems:



Where the velocities are vectors.

For example, say you have an bird flying west at 10m/s and you're in a boat travelling north at 20m/s, and you want to find the velocity of the bird relative to you.
Then since ,

Simply draw the velocity vectors and use geometric vector subtraction (remembering to reverse your vector!)
You can find the magnitude of the relative velocity using pythagoras, and its angle using trigonometry.

[Blakhitman]

Pretty sure relative velocity and such isn't in the course anymore?

At least according to my teacher it isn't.

[lachymm]

I came across one problem but it was simple eg you are travelling in a car 25 ms north and you see a car travelling towards you at 10 ms/s what direction and velocity is the car travelling at relative to you. Answer is 35 ms south.

[cameron_15]

its from the old study design.

It's easy though, and makes sense.