In the last 20 years geologists have begun measuring accumulation of helium (he) in some minerals because these minerals can retain he at temperatures up 100-200°c. the "date" gives a time when the material cooled below the temperature where the helium began to be retained, which is related to the depth of the material. where do you think the he comes from that allows this technique to work?

If vx = 7.00 units and vy = -7.60 units, determine the magnitude of v⃗ . determine the direction of v⃗ .

The pressure proportional to the area a- inversely b- directly c- increase d-decrease

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)