sign convention in 1D motion
How do I know when to take +ve and -ve while making equations? I had learnt that it's supposed to be according to the direction after setting one side as +ve and the other as -ve. But I wasn't able to solve questions using this, for example, I thought that g is always negative when positive is the upward direction but in solutions to questions online, the instructors take it was +ve or -ve in terms of direction of velocity.
Here is an example
https://youtube.com/watch?v=gN-KmBGSoYE
Here, shouldn't Va = -2Vb and not Va = 2Vb as Va and Vb are in opposite direction?
Thank you
Here is an example
https://youtube.com/watch?v=gN-KmBGSoYE
Here, shouldn't Va = -2Vb and not Va = 2Vb as Va and Vb are in opposite direction?
Thank you
