A 120-kg hollow spherical ball 1 m in diameter accelerates at a constant rate from rest to 5 rpm in 20 s and then continues to rotate at constant speed. The ball can be treated as a spherical shell. a. What is the moment of inertia of the disco ball? (3)
b. What is the angular acceleration of the ball in rad/s?? (5)
c. What is the torque delivered by the motor? (2)
d. Through how many turns does the ball rotate during the 20-s acceleration period? (7)
e. What is the tangential speed at t=20 s of a point on the surface of the ball at a distance 0.5 m (measured perpendicularly) from the axle? (3)

How many dots must be added to the symbol to properly represent a standard nitrogen ion? a) 1 b) 3 c) 5 d) 8

During physical science, ms. greene challenged her students to produce an energy transformation. james and jill wrapped a 4-inch nail with a coil of fifty turns of wire. they connected one end of the coil to one terminal of a knife switch. they connected the other terminal of the knife switch to the battery. finally, they connected the end of the coil to the other terminal of the battery. james held the tip of a 1-inch nail near the flat end of the 4-inch nail. jill closed the knife switch quickly and then opened it. the 1-inch nail was pulled toward the 4-inch nail. what is the best explanation of why the nail moved? a) electrical energy was converted to mechanical energy in the 1-inch nail. b) the 4-inch nail became an electromagnet and the magnetic force attracted the 1-inch nail. c) the electric current in the 4-inch nail was converted to mechanical energy in the 1-inch nail. d) the 4-inch nail had a positive charge and the 1-inch nail had a negative charge. opposites attracted.

You have a resistor and a capacitor of unknown values. first, you charge the capacitor and discharge it through the resistor. by monitoring the capacitor voltage on an oscilloscope, you see that the voltage decays to half its initial value in 2.70 miss . you then use the resistor and capacitor to make a low-pass filter. what is the crossover frequency fc?