Un automovil reduce su velocidad de21m/s a 7m/s en cuatro segundos, cual es su aceleracion​

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

conservation of mass

mass before something happens = mass afterwards