YOU ARE LEARNING:
Acceleration as a Vector
Acceleration as a Vector
The "direction" of acceleration is whether acceleration is positive or negative.
Acceleration is a vector ** quantity*, which means it has both a magnitude and a direction.*
Acceleration is a vector quantity, so it has both a magnitude and a direction
This woman is going from a speed of 3 m/s to a speed of 7 m/s. Is she speeding up or slowing down?
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/zMlKRF9RT9CKp44Njhuh.png)
The woman is speeding up from 3 m/s to 7 m/s
She does that over the course of just one second, so her acceleration is 4 m/s2
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/F9DcVeS3u8IoekMYBdmQ.png)
Now the woman is going from a speed of 7 m/s to 3 m/s. Is she speeding up or slowing down?
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/Sa3L5HtUTZmrJhKFat0O.png)
The woman is now slowing down again from 7 m/s to 3 m/s
She does that over the course of just one second, so her acceleration is now −4 m/s2
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/vCwnLpsDRkySdng0Wizs.png)
Acceleration's "direction"
What do you think we mean by the "direction" of acceleration?
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/6JQYxAQmRRCYbTGiDGNg.png)
When an object is speeding up, acceleration is _______________.
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/6JQYxAQmRRCYbTGiDGNg.png)
When an object is slowing down, acceleration is _______________.
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/6JQYxAQmRRCYbTGiDGNg.png)
Summary!
So the "direction" of acceleration refers to whether acceleration is positive or negative
If positive, like 4 m/s2, the object is speeding up. If negative, like −4 m/s2, the object is slowing down.
![](https://cdn.hejalbert.se/teen/blocks-images/en_GB/6JQYxAQmRRCYbTGiDGNg.png)