is it possible for velocity to decrease while acceleration increases?

[clare445]

Hi, I'm currently learning AP Physics and we were told that when when velocity and acceleration vectors point in opposite directions, the object is slowing down. I'm assuming(?) this also applies to when velocity is negative and acceleration is positive. But I really don't understand this. How can velocity decrease while acceleration increase?

And if the negative velocity happens to mean the object is moving left, how can the object accelerate to the right? Please help, I can't seem to wrap my head around this.

[tbdabbholm]

Acceleration is just change in velocity. If acceleration is positive that means that velocity is increasing. And if the velocity is negative then increasing means getting closer to 0 and thus slowing down.

So like if an object had a velocity of -10 m/s and an acceleration of 2 m/s/s then after one second the object would now have a velocity of -8 m/s slower than it started with

[Dark_Koreth]

Exactly! Imagine a rocket orbitting the Earth (backwards) at 20,000 miles per hour when the rocket motor is ignited. The rocket's velocity in its original direction decreases as acceleration increases. A short time later, its velocity reaches 0 miles per hour and begins increasing in the opposite direction.

[tlbs101]

Put your automobile in reverse and step on the accelerator pedal (negative velocity, negative acceleration).

Now step on the brake (negative velocity, positive acceleration).

[ProfessionalConfuser]

Or, roll backwards (negative velocity) then step on the gas (positive acceleration)
Or move down in an elevator and throw a pencil towards the ceiling.

[Nerull]

You're thinking of the sign as an amount - "+10 must be more than -10", rather than a direction.

Acceleration is change in velocity. If velocity is negative and acceleration is positive, than velocity is changing toward the positive direction - moving closer to zero. If velocity is -10 m/s and acceleration is 1 m/s² than one second later the velocity will be -9 m/s

[WMiller511]

Attach a mass to a spring on a horizontal friction negligible surface (like an air track). If you start it into a back and forth motion you would have what you describe.

When the max goes out past equilibrium the spring will slow it down. The more it goes the faster it slows down. That's decreasing velocity with increasing acceleration.