A cart of mass 0.68 kg is attached to one end of of a spring and placed on a low-friction track, inclined at an angle of 61.5 degrees with respect to the horizontal. The cart is found to be in equilibrium when the spring is stretched to a total length of 52.0 cm. Given that the rest length for the spring is 12 cm, what is the spring constant for the spring

Ais not a compound machine. a. bolt b. shovel c. handcart (dolly) d. see-saw (teeter totter)

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)

In a hydrogen molecule there are a total of four charges, 2 protons in the two nuclei, and 2 electrons. how many unique charge-pairs are there (without double counting)?