Your terminology is unclear. When a constant force is applied, there will be a constant acceleration with continuously increasing velocity. Your accelerometer should be reporting a constant non-zero value in that case. You seem to be implying with your "continuous" language that velocity is constant. In that case, there is no acceleration and the accelerometer should report a constant zero value. If this is not the situation, please clarify.

For experiment, I attached the accelerometer sensor on the table. Initially to test, I tap once on the table where the sensor is attached and I can see signal peak.

Then, I tap multiple times on the table at 1 sec interval. I can see only few peak.

Is it related to low sampling rate or MEMS is not good for the same (or piezoelectric accelerometer is good)?

what kind of accelerometers are using in your work

accelerometer and sensors have different starategies.

It is a MEMS analog sensor 1.5g and 3.0g.