- #1

- 21

- 0

If no velocity are given, and you only know that the acceleration is, say, a= -5 m/s^2, how do you know the object is going forward or backward?

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter sallychan
- Start date

- #1

- 21

- 0

If no velocity are given, and you only know that the acceleration is, say, a= -5 m/s^2, how do you know the object is going forward or backward?

- #2

NascentOxygen

Staff Emeritus

Science Advisor

- 9,244

- 1,072

IIf no velocity are given, and you only know that the acceleration is, say, a= -5 m/s^2, how do you know the object is going forward or backward?

Hi sallychan. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

You don't know anything about the current velocity (or displacement) when all you are told is acceleration.

Last edited by a moderator:

- #3

arildno

Science Advisor

Homework Helper

Gold Member

Dearly Missed

- 9,970

- 134

That is an arbitrary choice WE make!

When we use the concept of RETARDATION then that means the acceleration is in opposite direction of the velocity, where "opposite" means along the same line the velocity lies, but in the other direction (that is, 180 degrees shifted from the velocity direction). Retardation always reduces the SPEED of the object.

If the acceleration is ORTHOGONAL to the velocity, that is with a direction 90 degrees to the direction of the velocity, the acceleration will not change the speed of the object, but will make its trajectory curved, the sign of the acceleration telling us to "which side" the object will curve. We call such acceleration centripetal acceleration.

Share:

- Replies
- 4

- Views
- 18K

- Replies
- 3

- Views
- 18K