Angel is setting off fireworks on New Year's Eve. The fireworks are plugged into the ground. Fireworks shoot upwards at a speed of 20 m/s and emit a sound with a frequency of 936 Hz. After moving 1.2 seconds, the fireworks explode and produce a sound with a lower frequency of 609 Hz, but with an amplitude 10 times the previous sound. Just before the fireworks shot upwards, Angel retreated at 5 m/s, then stopped as the fireworks began to slide. It is known that the speed of sound in air is 340 m/s. a. How did Angel hear the fireworks for the first second?

b. What frequency does Angel hear when the fireworks explode?

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation: