You see your friend 100 m away down the street. if you yell back and forth, your conversation will be affected by the speed of sound, which is 340 m/s. if, instead, you use your cell phone to call her on her cell phone, the conversation is relayed via a communications satellite that is 36000 km above you. what is the delay between a sound leaving your mouth and its arrival at your friend’s ear if (a) you yell, or (b) you use your cell phone? (c) how far would you have to be from your friend for the delays to be equal?

(a) 0.29 s

If you yell, your voice will reach your friend by travelling as a sound wave through the air.

The speed of sound in air is

v = 340 m/s

while the distance to be covered is

d = 100 m

So, the time taken is

(b) 0.24 s

In this case, the voice is transmitted as a radio wave (electromagnetic wave) to the satellite and then back.

The speed of electromagnetic waves is the speed of light:

while the distance the wave has to cover is twice the distance between the ground and the satellite:

So, the time taken is

(c) 81.6 m

In order for the two delays to be equal, the distance between you and your friend (d') must satisfy the equation

where on the left is the time taken by the sound to travel through the air, while on the right is the time taken by the radio wave to travel back and forth from the satellite.

Solving the equation for d',

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:

reserve is the answer