Electromagnets are created by a. applying a charge to a magnetic material, wrapped in an insulator, which creates an electromagnetic field around the magnet. b. covering a magnet with insulation and applying an alternating electrical current to the magnet. c. twisting a ferromagnetic material, wrapping in an insulator, and applying a direct current to the coil. d. wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s.when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?