Timeline for Gravitational Acceleration $g$
Current License: CC BY-SA 3.0
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| when toggle format | what | by | license | comment | |
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| Jan 10, 2018 at 7:15 | history | edited | Steeven | CC BY-SA 3.0 |
added 113 characters in body
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| Jan 10, 2018 at 7:12 | comment | added | Steeven | @AmritDas Imagine a ball falling. Weight $w=mg$ pulls downwards. Air resistance $D$ pulls upwards. If we choose an axis pointing upwards, then we will write $$D-w=m(-a)\Leftrightarrow D-mg=m(-a)$$ The weight $w=mg$ is negative due to our choice of axis. Not $g$, but $w=mg$. If we choose an axis pointing downwards, then we will write $$-D+w=ma\Leftrightarrow -D+mg=ma$$ Here the weight $w=mg$ is positive due to our choice of axis. As you see, we are never dealing with a sign for $g$, only with a sign for the force. And signs only depend on choice of axis. | |
| Jan 10, 2018 at 6:38 | comment | added | ADR | Yes i asked this question with refering to coordinate systems. It is said that g will be negative for upward or downward motion if we take upward direction as increasing or positive direction. Moreover g will positive if take downward direction as increase or positive direction. These two points are making me confused. How to understand them? | |
| Jan 10, 2018 at 6:08 | history | answered | Steeven | CC BY-SA 3.0 |