Pages: 1 [2]   Go Down
Author Topic: Accelerometer for sensing how fast a poi is spinning?  (Read 2208 times)
0 Members and 1 Guest are viewing this topic.
Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 525
Posts: 26554
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

"Why is general relativity mentioned here?"
Well, if it goes fast enough, it will really seem to be going slower, compared to us?

What'd you see on your vacation today? Did you join the mass of 800,000 people at the fireworks?
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

0
Offline Offline
Shannon Member
****
Karma: 200
Posts: 11730
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
as a matter of fact, the acceleration is only 2g but since accelerometer only measures force, it reports 3g

That depends whether you are working in an inertial reference frame....  3D accelerometers are neat precisely because they understand F=ma and general relativity!  They only read zero in free-fall.

Which part depends on inertial frame? 2g acceleration or 3mg force measured by the accelerometer?
Why is general relativity mentioned here?

According to general relativity there is no difference between acceleration due to gravity and any other kind... No experiment can distinguish them.  In particular an accelerometer can't so it sees an acceleration of 3g at the bottom of the swing caused by the tension of 3mg in the string.
Logged

[ I won't respond to messages, use the forum please ]

Pages: 1 [2]   Go Up
Jump to: