Magnetic fields within a sunspot can be as strong as $0\mathrm{.}4$ T$.($By comparison, the earth$$s magnetic field is about $1/10,000$ as strong.$)$ Sunspots can be as large as $25,000$ km in radius. The material in a sunspot has a density of about $3*10^-4$ kg$/$m$^3.$ Assume for the sunspot material is $\_0.$ If $100\%$ of the magnetic field energy stored in a sunspot could be used to eject the sunspot$$s material away from the sun$$s surface, at what speed would that material be ejected? Compare to the sun$$s escape speed, which is about $6*10^5$ m$/$s$.($Hint: Calculate the kinetic energy the magnetic field could supply to $1$ m$3$ of sunspot material.$)$

Ans. $20$ km$/$s; about $30$ times smaller