kinematics question, need help!

[yabbaboo]

thankyou for your help!! Just one more question (sorry if it sounds stupid!), why T-28g?

[b^3]

thankyou for your help!! Just one more question (sorry if it sounds stupid!), why T-28g?

Since I initially took down the slope as positive, that means that for the 28kg mass, the positive direction would be up. At first we don't know which way it will move, so I set up the two equations with the positive direction as above. So it looked as if the block was moving down the slope, so T would be greater than 28g since it was mving up, so T-28g. But we end up with a -ve acceleration so it is moving in the opposite direction i.e. up the slope.

EDIT: make sure that you have the blocks set up so that the same direction is positive, that way the equations will be set up the right way.

[dc302]

Lol I know I'm just being pedantic but g is (at least in spesh) used as the number, not the acceleration. Ie, g=9.8, not 9.8 m/s^2

Nothing wrong with being pedantic

But what is the reasoning behind not writing m/s^2?

It's also simpler to use letters for numbers by themselves, rather than with units. For example if you wanted to have a speed at 9.8m/s, and g = 9.8 m/s^2, then your speed is like 9.8s (which looks weird). But yeah, as b^3 said, VCAA uses this as a convention anyway.