a vertical pulley has a radius of 5 cm. A thin string is wound around the outside of the pulley, and a weight of 8 N is suspended from it. The pulley has a brake, located 3 cm from the pulley's axle. how much force must the brake exert to keep the pulley from turning?

Suppose a wire with a current is pushed upward by a magnetic field. how would the wire move if the direction of the current reversed? explain your answer.

What are the necessary conditions for fusion?

The space between two 15-in.-long concentric cylinders is filled with glycerin (viscosity = 8.5 × 10-3 lb·s/ft2). the inner cylinder has a radius of 1 in. and the gap width between cylinders is 0.1 in. determine (a) the torque and (b) the power required to rotate the inner cylinder at 180 rev/min. the outer cylinder is fixed. assume the velocity distribution in the gap to be linear.