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multiple !
which of the following is true about magnetic field lines at the north pole and south pole of a bar magnet?

a. field lines begin near the center of the magnet and extend toward the north and south poles.
b. field lines begin near both the magnet’s north and south poles and meet in the middle.
c. field lines begin near the magnet’s north pole and extend toward its south pole.
d. field lines begin near the magnet’s south pole and extend toward its north pole.

Plzz worth 10 ! which statement about energy transformations is not true? a all forms of energy can be transformed into thermal b energy is never destroyed or created during transformations c potential chemical energy always transforms into kinetic d some thermal energy is always released during a transformation

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)

A20 cm long spring is attached to a wall. the spring stretches to a length of 22 cm when you pull on it with a force of 100 n. what is the spring constant