Until a train is a safe distance from the station it must travel at 5 m/s. Once the train is on open track it can speed up
to 45 m/s. If it takes a train 8 seconds to reach 45 m/s, what is the acceleration of the train? (Round your answer to
the nearest whole number.)
A• 4 m/s2
B• 5 m/s²
C• 6 m/s2
D• 7 m/s2

The ultracentrifuge is an important tool for separating and analyzing proteins. because of the enormous centripetal accelerations, the centrifuge must be carefully balanced, with each sample matched by a sample of identical mass on the opposite side. any difference in the masses of opposing samples creates a net force on the shaft of the rotor, potentially leading to a catastrophic failure of the apparatus. suppose a scientist makes a slight error in sample preparation and one sample has a mass 10 mg larger than the opposing sample. if the samples are 12 cm from the axis of the rotor and the ultracentrifuge spins at 70,000 rpm, what is the magnitude of the net force on the rotor due to the unbalanced samples? ( be thorough on your answer)