# Velocity vs acceleration

1. Aug 30, 2009

### hasanhabibul

1)a body having zero velocity but acceleration not zero...and 2)a body having constant velocity and variable acceleration....which one is impossible. or both are correct or neither is.

2. Aug 30, 2009

### Staff: Mentor

What do you think?

3. Aug 30, 2009

### IBY

@hasanhabibul
For the first one, think about a ball being thrown up, stopping, and going down.

4. Aug 30, 2009

### hasanhabibul

i think both are impossible....both seems to be very strange to me...but myresult is not correct..i have known it from the answer....at least both will not be impossible....either or both will be possible ..

5. Aug 30, 2009

### Staff: Mentor

(1) What about IBY's example of a ball tossed straight up in the air? What's the acceleration? What's the speed at the very top of the motion?
(2) What's the definition of acceleration?

6. Aug 30, 2009

### IBY

If the ball slows down, that means there is a force, ie. gravity. If there is a force, what does that imply that there is? Plus, after the ball slows down and stops, it goes down again, which means that force is still being applied. Note, velocity is changing throughout the whole process.

7. Aug 30, 2009

### hasanhabibul

ohh thnx both of u.....i got it