Aboy and his skateboard have a combined mass of 65 kg what is the speed of the boy and skateboard if they have a momentum of 275 kg•m/s

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

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)

Where is the potential energy throughout the loading, cocking, and releasing of the trebuchet?