Question

what is relative velocity? where should we apply it?

Answer 1

https://www.youtube.com/watch?v=hRBE5sdMD8c

Answer 2

umm....can you explain it pls

Answer 3

What part didn't u get in the video?

Answer 4

how we should appy it?

Answer 5

Imagine a 100 meter train is at rest.. and a parrot is flying across it with 2m/s.. how much time does it take for the parrot to cross the train?

Answer 6

50s

Answer 7

Correct
now imagine the train is also moving, in the opposite direction of the parrot at 18m/s second

how much time will NOW the parrot take to cross the train?

Answer 8

50/9sec=5.55

Answer 9

o.O
what?. how did you get that?

Answer 10

speed =dist/time

Answer 11

is it correct?

Answer 12

But.. since both are moving, how do you know, how much the parrot has to travel before it crosses the train?

Answer 13

okay so what should I do?

Answer 14

imagine u are inside the train, and consider yourself stationary

then. what will be the speed of the parrot as seen by u?

Answer 15

-20 m/s.....

Answer 16

Correct!

Answer 17

so now you can find what the time taken by the parrot is!

Answer 18

thanx a lot @mashy

Answer 19

your welcome..

hope u calculated that the parrot now takes only 5 seconds to cross the train

what this tells me is that the parrot only flew 2* 5 = 10m, and by the time he flew 10 meters, the train covered 18* 5 = 90 meters, and so the parrot was able to cross the train

see its much easier to do such calculations using relative velocity :)