Jump to content
  • 0
Sign in to follow this  
dndfuf98

Ap physics 1 essentials 2nd edition

Question

For #2 of the Gravity part of the AP style problem, I'm not sure why speed has to increase in order to increase the radius. I thought speed has to decrease because of the inverse relationship with radius according to the derived equation, v = square root of Gm/r.

Share this post


Link to post
Share on other sites

1 answer to this question

Recommended Posts

  • 0

That is a FANTASTIC question, and to answer it, we need to understand that by accelerating at the top position, we're no longer maintaining a circular orbit, but setting up an elliptical orbit.  If we increase the speed of the satellite in that top position, we've increased the kinetic energy of the satellite at that position.  But a more complete orbital analysis must take into account gravitational potential energy.  By increasing the kinetic energy at the top position, we'll trade that speed off for gravitational potential energy at the bottom position.  The following web page goes into more detail (https://www.physicsforums.com/threads/orbital-speed-faster-is-closer.733175/), but the best way I've found to get a good feel for orbital mechanics is to play games.  As mentioned on the thread above, Orbiter is a free game that will give you a good feel for it, but Kerbal Space Program is a lot more fun in my opinion (though it's not free).  :-)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

Terms of Use

The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.

Copyright Notice

APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to info@aplusphysics.com. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.

×