# Old speed/trajectory problem

1. Sep 21, 2007

### HeLLz aNgeL

https://www.physicsforums.com/showthread.php?t=62644

can anyone figure out how to do this ? because the sole reply that the thread got, doesnt seem to work for me..

thanks !

2. Sep 21, 2007

### Staff: Mentor

What is not working?

The attachment reads -

$$\vec{r} = A (1 m/s)t\hat{x}\,+\,A[(1 m/s^3)t^3-6(1 m/s^2)t^2]\hat{y}$$

3. Sep 21, 2007

### HeLLz aNgeL

yes, but i cant seem to solve the questions it asks :P

4. Sep 22, 2007

### HeLLz aNgeL

bump ... help please !

5. Sep 23, 2007

### learningphysics

Did you take the derivative of $$\vec{r}(t)$$ to get $$\vec{v}(t)$$? What did you get?

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