The discussion focuses on determining the signs of the vertical coordinate (y) and gravitational acceleration (g) in kinematic equations. It is established that if the positive y-direction aligns with gravity, g is +9.8 m/s²; if it opposes gravity, g is -9.8 m/s². The conversation emphasizes the importance of context and personal choice in defining the coordinate system. Additionally, it suggests that using vector algebra and calculus can clarify these concepts and reduce confusion regarding sign conventions.
PREREQUISITESStudents studying physics, educators teaching mechanics, and anyone seeking to clarify the application of kinematic equations and gravitational effects in problem-solving.
There's no way to figure it out. It's your choice! Gravity is always directed towards the Earth - there is no choice about that.bluesteels said:Summary:: i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8
i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8
Most textbooks would already insert the minus sign in the latter case, so you would still replace g with 9.8.anuttarasammyak said:If +y has same direction with gravity, it is 9.8.
If +y has opposite direction with gravity, it is -9.8.
Every rextbook does it differently. You would need to look at the relevant chapters and read some of the worked examples.bluesteels said:Summary:: i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8
i was doing some problem and i have a hard time figuring out when will the y be positive and negative and same with the gravity idk if it -9.8 or 9.8