m1 gravity

So you're one of those guys smh

illogical

So you're one of those guys smh

illogical

Not really, it seems logical to me.

A lot of the books on mechanics and analytical dynamics take upwards as +ve most of the time.

tbh i still dont get it

sometimes s is a negative

sometimes g is a negative

you guys said choose which way is negative, wtf does that mean

still confused

Just ask your teacher.

tbh i still dont get it

sometimes s is a negative

sometimes g is a negative

you guys said choose which way is negative, wtf does that mean

still confused

If an object is falling only it makes sense to take gravity as positive.

If an object is going upwards then it would make sense for the velocity to be positive but gravity to be negative as the gravity is opposing the direction of motion.

A good way to see it is if an object is moving in the same direction as gravity then you can make both of them positive but if the object is moving in the opposite direction to gravity you can make velocity (and likely displacement) positive and gravity negative.

Finally, someone who uses up as negative

If an object is falling only it makes sense to take gravity as positive.

How about if the object is projected upwards and you want to find the greatest height? In that situation the motion and diplacement are positive but acceleration is negative so one could argue that it makes more sense (and fewer negatives in the working) to set upwards as positive?

Personally I like to encourage students to try taking both upwards and downwards as positive and not to stick to one rigid method.

If it is going up and down it isn't falling only which is what I said before.

If I have a projectile being shot up and then falling back down I will take displacement and initial velocities as positive and gravity as negative. Mainly because I haven't seen a single question where the object lands lower than the original height other than when it is "only falling". This way there are less negatives which is nicer

Only sometimes though.