Hi,
Can you please post a picture(s) of your project so we can see your component layout?
In what axis are you rotating the 6050?
Thanks.. Tom.... 
s it rotates
Yes it rotates.
OK I will ask a little bit more precise:
does the mpu6050-sensor rotate together with the microcontroller?
Will the mpu6050-sensor and the micrcontroller be placed together in a box where the whole box will rotate?
s they will be together only
I don't understand this
can you please answer with "no" or "yes"
Will the mpu6050-sensor and the micrcontroller be placed together in a box ?
Answer with "no" or "yes"
Will the whole box rotate? please answer with "no" or "yes"
yes
OK interesting ping-pong-game
I had a first question
1: Will the mpu6050-sensor and the micrcontroller be placed together in a box ?
Answer with "no" or "yes"
2: Will the whole box rotate? please answer with "no" or "yes"
can you please specify
1: Yes
2: Yes
yes the sensor and microcontroller fitted in a box will rotate
Ok Thank you
New question what is the range of the rpm (rotations per minute) that can occur?
range of a normal car
So the final purpose of measuring this is a RPM-display in a car?
yes , i am measuring RPM of my car
can you post a picture of the rotating part where you want to mount the
microcontroller and the sensor?
the coloured part will be my sensor and i am going to make a cas to hold it in place
i got it to detect speed of a car i will use a speed sensor
Aha. Hm mounting it at this position will dis-balance the wheel.
Usually car-wheels are balanced carefully down to the range of 5 grams on a balancing machine that analyses where to place a 5 gram 10, gram maybee 20 gram weight made out of lead.
Which is then stuck to the inner side of the wheel so that the centrifugal force is helping to keep the weight in place.
With mounting your box on the side the centrifugal forces will be so great that you would have to drill wholes into the rim and tighten your box with screws.
With any glue it will fly away.
But then any insurance will say uncertified modification of the rim we don't pay
You will have a permanent radial load that makes your car vibrating.
You would have to seal it completely to avoid water coming in if the street will be ever wet. This sealing has to be of the highest quality possible.
The signal out of the mpu6050-sensor will be an increasing g-force-signal that will be disturbed by any bumb of the car
So my recommendation is to use something completely different for measuring the rpm.
I feel somehow sorry to say that. But that is the truth that will prevent you from going down longer on this path that is very likely to turn out into not working.
Your title says speedometer that means measuring speed. That is something different than rpm.
What do you really want speed or rpm?
For speed you could use a GPS-module
https://www.google.de/search?as_q=Arduino+gps+speed
For measuring rpm: rpm of the motor or rpm of the wheel?
Or just use an GPS-based app in your smartphone
No fun with programming but ready to use
https://www.wish.com/product/5df8680fd0ac86072db93baa
what's the fun in it . not useful
OK. Finally you were able to reveal what your project is. You seem to have not read every line of post #39 ( the long one) I recommend reading it carefully.
After reading it you will have a better base to decide if you want to go on using the mpu6050-sensor on the wheel or something else.
I decide to stop my support at this point. I will adjust the thread to muted.
As long as you don't hurt other people you are free to make experiences of your own choice.
May the force be with you when you discover the answer is "42"