Acceleration and Velocity (1 Viewer)

[BlueGas]

I just need some clarifying on what's in the red box, I know that if the velocity if negative it's travelling to the left (negative direction), but I know that acceleration, if negative, decreases in speed, but the answer says speeding up? Am I wrong? Can someone clarify for me?

 

[Drsoccerball]

I just need some clarifying on what's in the red box, I know that if the velocity if negative it's travelling to the left (negative direction), but I know that acceleration, if negative, decreases in speed, but the answer says speeding up? Am I wrong? Can someone clarify for me?

If your acceleration is less than 0 and your speed is positive it slows you down untill you stop. But then since theres still acceleration on the object it still needs to go somewhere so it goes into the direction thats pulling it and therefore speeds up in the negative direction

 

[flavurr]

If an object is speeding up, its acceleration is in the same direction as its motion. SO since v<0 and a<0 the particle is speeding up in the negative direction.

On the contrary, if v>0 and a>0 then the particle is speeding up in the positive direction

 

[BlueGas]

So if it was v<0 and a>0 then the particle is moving in a negative direction at decreasing speed?

 

[Drsoccerball]

So if it was v<0 and a>0 then the particle is moving in a negative direction at decreasing speed?

Yes. Depends on what you define as decreasing speed. As the velocity is actually increasing.

 

[BlueGas]

Yes. Depends on what you define as decreasing speed. As the velocity is actually increasing.

You mean the acceleration is increasing?

 

[InteGrand]

You mean the acceleration is increasing?

If a > 0, velocity is increasing, and acceleration need not be increasing (because just because a function (acceleration in this case) is positive, doesn't mean it's increasing). Velocity is increasing though if a > 0 because by definition, a = dv/dt (rate of change of velocity).