## anonymous 4 years ago From my previous question : At the moment the train’s speed is 45 km/h, what is the magnitude of the total accelera- tion? Answer in units of m/s2

1. anonymous

First convert 45 km/hr

2. anonymous

12.5 m/s

3. anonymous

heres where` the r comes from?? v^2/r

4. anonymous

.959

5. anonymous

It doesn't matter what the speed is. The earlier prompt says "slows down at a constant rate" which means the train experiences constant acceleration.

6. anonymous

which is?

7. anonymous

can you explain this further.

8. anonymous

You're right. I overlooked the circular part. $a = {v^2 \over r}$

9. anonymous

But that is only the centripetal component, there is still the tangential. We are asked for the total magnitude. $a = \sqrt{\left(v^2 \over 2 \right)^2 + a_t^2}$where $$a_t$$ is the acceleration value you found in the other question.