The engineer of a passenger train traveling at 25.0 m/s sights a freight train whose caboose is 200 m ahead on the same track. the freight train is traveling at 15.0 m/s in the same direction as the passenger train. the engineer of the passenger train immediately applies the brakes, causing a constant acceleration of magnitude 0.1 m/s2 . will the trains collide? if so, where do they collide? (take = 0 m to be where the passenger train is when the engineer hits the brakes) if not, what is the smallest distance they will be apart?

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)