Why it is so painful to be stepped on accident by high-heel shoes?

Very high pressure on your foot.

Explanation:

Now let's say this lady who stepped on your foot is 70 kg. The force she exerts is her weight which is about 700 N.

Now, if those 700 N are spread over a larger surface area, as in flat shoes, the pressure she'll exert on your foot will be much less than if her 700 N were concentrated on the tiny heel's surface area.

According to the formula,

P= F/A; where P is pressure in Pa, F is the force in N and A is the surface area in metre square;

Pressure is inversely proportional to area. The smaller the area the higher the pressure exerted. And that's the case with the heel.

12000j is work done

need to see circuit to get time constant