6.a motor pulls an 800 kg roller coaster train to the top of a 75 m hill. what is the change in the potential energy of the cars? a.5.9 x 10 ⁵ j b.6.0 x 10 ⁴ j c.18 x 10 ⁴ j d.7.5 x 10 ⁵ j 7.friction converts kinetic energy to which form? a. potential energy b. mechanical energy c. non mechanical energy d. total energy 8.how much power does a crane need to lift a 200.0 kg mass at a speed of 2.300 m/s? a. 460w b. 1962w c. 4513w d. 6123w 9.if a 50.0 kg cheetah, initially at rest, runs 274 m north in 8.65 s, what is its momentum? a.31.7 kg m/s b.1584 kg m/s c.490.5 kg m/s d.118,500 kg m/s 10.what is the kinetic energy of a 0.005 kg raindrop that falls 250 m? a.4.9j b.1.25j c.8.3j d.5.6j

All the simple machines make work easier to do by changing the or of a force. a. size; type b. work; type c. size; direction d. type; direction

J. j. thomson’s experiment disproved the theory that an atom

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)