fast movements triggers vibration

Hi, I am seriously struggling with what I though was going to be a simple task. I want to create a handheld object that if it is moved at a fast speed, will vibrate. I have an arduino, 3-axis accelerometer and vibration motor however do i need a gyro instead? it doesn't have one included in the accelerometer. I have found code that allows me to see the movement upon the 3 axis' in the serial monitor however am i able to then translate these into thresholds that trigger the vibration?

I am a total beginner to this, please talk like I'm completely stupid

thank you thank you

Gyro senses orientation, accelerometer senses acceleration. Yes, you should have a threshold to trigger the vibration.

I presume that by "moved at a fast speed", you mean accelerated briskly such as by being shaken.

An accelerometer does not measure speed directly, it measures acceleration - the change in velocity, including a change in direction of movement. You can integrate the acceleration measurement to determine speed, but this presumes you knew the original speed when the process of integration was started and requires very accurate measurement as the integration process amplifies error.

One obvious complication is that your vibrator motor will of course, accelerate the device vigorously and make further measurement of externally applied acceleration impossible. That would obviously imply that once started, it would perpetuate its own vibration.