A pulley is used to raise a heavy crate. With the pulley it only takes an effort force of 223 N to provide a resistance force of 1784 N. What is the mechanical advantage of this pulley?

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?