Wrong Direction

[kenhung123]

Firstly I want to ask is force a vector quantity?

What happens when the direction isn't specified by the quantity your dealing with is a vector and lets say I got -12m/s but the actual answer is 12m/s (it did not specify direction) would I lose marks?

Could I possible just ignore negative answers (due to direction) if it does not ask?

[TrueTears]

F = ma

m is a constant, a is a vector, the final result is a vector.

+ and - signs are definitions, you define them at the start of the question, -12m/s could mean exactly the same as 12m/s if u defined - as to the right but the answers may have defined + to be the direction in the right.

[googoo]

When the acceleration of an object is e.g. -1 m/s2, does it mean the object is slowing down?

[m@tty]

It means that it's velocity is reducing. But this is not always the same as speed reducing which is what I interpret "slowing down" as implying.

For example if a = - 1 m/s^2 right   Then the velocity to the right will be getting more negative. ie. it could progress from 2 -> 1 -> 0 -> -1 -> -2 etc.  After the velocity passes below the speed actually starts increasing -- Speed = |velocity|...

[kenhung123]

Hmm are we supposed to define the direction in each question which involves a vector quantity? E.g. at start saying down is positive.

[TrueTears]

Hmm are we supposed to define the direction in each question which involves a vector quantity? E.g. at start saying down is positive.

yah unless its done for ya

[kenhung123]

Just to confirm so if I use gravity=-10 that means up is positive right?

[Chavi]

Just to confirm so if I use gravity=-10 that means up is positive right?

Ye, always specify the direction, cause it's a vector quantity.
To avoid getting confused, it's probably just easier to say 10m/s2 down/up/left/right

[Blakhitman]

Just to confirm so if I use gravity=-10 that means up is positive right?

Ye, always specify the direction, cause it's a vector quantity.
To avoid getting confused, it's probably just easier to say 10m/s2 down/up/left/right

To do the maths you need to assign direction though.