Homework Help: Motion in a circle

1. Apr 25, 2005

fern

heh! this is my first post!!
ok... ive been trying to do this for ages, i think im just doing it the wrong way... its holiday homework so i couldnt ask my teacher
i drew a diagram but i think i did it wrong... im just not getting the right answer!
ok here it is
part of a roller coster track is in the shape of a vertical circle of radius 300m. what is the slowest speed the roller coster can have at the top of the loop so that all the centripetal force is supplied by the roller coaster's weight? :yuck:
could someone please explain how to do this!!
stank you!

2. Apr 25, 2005

arildno

Allright:
Given velocity and radius of the circle you're moving on; what's the centripetal ACCELERATION you experience?

3. Apr 25, 2005

kusal

As far as I know the answer is
centripetal force=weight
mv^2 /r= mg
v=54.221 m/s

4. Apr 25, 2005

arildno

Looks good to me; the answer is wrong.

5. Apr 25, 2005

fern

argh!!! thank you!!! heheh that answer (5,86) was in the back of the book! i hate it when they make mistakes it just confuses me!!
i propbaly would have got it if the answer was right!!!
thank you so much!