Calculating Weight and Velocity on a Circular Track: Formulas and Examples

[physics-dummy]

Homework Statement

:

#1. You are walking on a perfectly round asteroidwith a diameter of 40km and a mass of 10 to the 16th kg. your mass is 60kg. how much will you weigh, in Newtons?

#2 a 100 kg porshe is moving at a steady speed around a cicular track waith a 1000 m radius. The porshe's centripedal acceleration is 5 m/s squared. What is the magnitude of its velocity?

Homework Equations

The Attempt at a Solution

I tried a=v squared/r but it doesn't include the mass so i didn't think it's right and I've looked through all my notes and can't find a formula for the second one. For the first one I'm lost cause f=ma don't work. any help i would be grateful for, thanks.

 

[Dick]

You are on the right track for the second one, and you don't need the mass. On the first one look up Newton's law of gravitation.

 

[physics-dummy]

thank you very much. after i get 71 for the second answer how do i change it into km/hr

 

[Dick]

Put units on things, ok? If you got 71m/sec and you really want to convert to km/hr, then 1m=km/1000 and 1sec=hr/3600. Now what? Units are your friends, they help you from being confused.

 

[physics-dummy]

Thanks for the help.