How to check RPM of motor?

Question

Hi:

How to check RPM of any motor?

Or any other thing, like car tires?

I have searched enough, but can't find any device!

Answer 1

Squint your eyes and count how many times it rotates in a minute.  It may take some practice but you will be able to do it eventually.

Answer 2

I assume this means your car does not have a tachometer.  If it did, just read it off the gage

You can also calculate it using your speed, tire diameter, and gear ratio.

Answer 3

Try searching for "tachometer" there are a wide range of devices available. Non-contact tachometers that use an optical sensor are popular, and can be used on almost anything on which you can put a reflective mark (or non reflective if the rotating part is already reflective)  

Answer 4

You can can check the rpm of a motor shaft with a mechanical or electronid tacxhometer.

Answer 5

RPM stands for revolutions per minute.

Simple way to measure is to count the revolutions that happen in one minute. This can be done with a sensor like a tachometer or if the motion is slow enough by eye. Other devices used include a resolver or an encoder can measure shaft rotation and be used to compute RPMs.