The enlargement of the somatosensory Area for a dominant fingers in violin players in is an example of the effects of

force is mass*acceleration.

we have a very small mass: 11.4*0.001 kg

if we want 0.035n of force, we need an acceleration:

0.035 = 11.4*0.001*a

a = 0.035/(11.4*0.001) m/s^2

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.