What does it mean if an object has negative acceleration

[AllieBrown]

[Mosaic]

Could it mean, it's going backwards?

[ChuckFickens]

it's slowing down.

[bibblebub]

v = u + at

If t < u / mod(a) then v > 0 but decreasing with time.

if t = u / mod(a) then v = 0

if t > u / mod(a) then v < 0 and increasing in magnitude

[rov1200]

Decelarating. eg from 50m/s/s to 40m/s/s

[factor-fiction]

As others have said it could be slowing down. Or maybe it is accelerating in the opposite direction from that being considered?

[wildwood]

Mmm... not many choices left.... I'll pick assisted slowing down such as braking or reverse engines' thrust.

[philkool]

Run out of fuel ?

[R1Geezer]

Deceleration derr!

[mollykins]

It could mean decelleration or if you are using velocity, it could be accelerating in a negative direction, which could be going backwards faster or its turned around and is accelerating forwards.

I think, we've done about this kind of thing is gcse science.

[mollykins]

*in*

[Azalian]

Negative acceleration is a decreasing rate of acceration or deceleration.

Acceleration in "the opposite direction" is positive acceleration in THAT direction, since acceleration is a vector quantity, that is it has magnitude (size) and direction.

[Avatar]

Acceleration a vector quantity? I think not.
For instance 'g' is an acceleration force, gravity, is it not? Which perhaps may be vector based, but 'g' is also felt in a centrifuge and your net vector distance covered in a centrifuge would be nil.
You only have to watch Moonraker to see this...