#### ADWSystems

##### Member

The goal is to design a system that works, select a sensor that will provide readings that are within the reasonable range. It isn't and doesn't have to be calibrated. The results will not be converted to engineering units. The impact detector is to help soccer players (kids learning) to kick the properly and accurately for the most power. The result will be 0-999 displayed on a 3 digit 7-segment display. The system will be using a 10-bit ADC and I will drop the last 25 counts to make it fit.

Now for the physics problems.

Problem #1.

Known: Soccer ball, size 4, weight about 0.45 kg.

Known: Free floating target 1 meter square of 3/8" plywood (about 4kg). [Yes free floating let's get the concept down first, then get complicated]

Unknown: Soccer ball velocity

Measurement: Acceleration of target (using Analog Devices ADXLxxxx chip, TBD)

Assume measurement A = 1 = 9.8m/s2

Target: F=mA = 4 * 9.8 = 39.2

Ball: Don't know A, can't use F=mA, assume constant v, use F=1/2*mV2 -> V=sqrt(2*F/m); where F=39.2 = sqrt(2* 39.2 / 0.45) = sqrt(174.2) = 13.2 m/s

According to the internet, this is a reasonable number. Question: Do I have the physics math correct?

Now get complicated:

Known: Soccer ball, size 4, weight about 0.45 kg.

Known: Target 1 meter square of 3/8" plywood (about 4kg), hanging by its top edge.

Unknown: Soccer ball velocity

Measurement: Acceleration of target (using Analog Devices ADXLxxxx chip, TBD)

Assume measurement A = 1 = 9.8m/s2

Target: F= ??

Ball = F=1/2mV2 then use F from the target above.

I'm thinking it needs the moment of inertia or some other factor. (Since I don't know where the force from the ball will be applied, I am going to assume the center).

How do I calculate F for the 1m square 4kg target hanging from the top edge and the force applied to the center?