think you are walking tword the back of a bus that is moving forward with a constant velocity. describe your?

Question

motion relative to the bus and relative to a point on the ground

Answer 1

relative to the bus, you are going backwards at your walking speed. Realtive to the ground you are walking forward with a speed of the speed of the bus - your walking speed

Answer 2

All velocities are relative...relative to some sort of framework. In your case v(bus), the walker's velocity re the bus, is what you will see entirely within the bus (without looking outside). Thus, if all the bus windows were blackened, the only velocity you'd see is that walker walking to the back of the bus. That's his velocity relative to the bus.

But v(out), is what you see while sitting at the bus stop watching your bus whiz on by without stopping. You see the walker whiz by you along with the bus, but you also see, through the windows, that the walker is heading towards the back of the bus. But in the end, the walker is not walking fast enough to offset the bus's velocity; so he and the bus both whiz on by without stopping.

This may be one of the most important physics lessons you'll ever learn...that is, all velocities are relative to frameworks. In your case you had two frameworks: the bus and the ground outside the bus. Anyway, you should know the theory of relativity is relative because of the frameworks the velocities are measured relative (get it) to. And that's why this lesson is so important to understand.