What might be the mass of a positive ion that is moving at 1.0*10^7m/s and is bent into a circular path of radius 1.55m by a magnetic field of 0.134Wb/m^2?

The astronauts on the space shuttle flights experienced an acceleration of 29 m/s2 (about 3 "g's") during lift-off. what upward force must the astronaut's seat apply to the astronaut in order to cause this acceleration? assume the astronaut's mass is 70 kg, and compute this force when the acceleration is near the earth's surface so their weight equals latex: mg m g .