Wavelength = speed / frequency
(345 m/s) / (20,000 Hz) = 0.017 m
Answer:


-0.020475 V
Explanation:
= Vacuum permeability = 
= Number of turns of coil = 25
= Number of turns of coil 2 = 300
= Rate of current increased = 
d = Diameter = 2 cm
r = Radius = 
A = Area = 
Magnetic field in the solenoid is given by

Magnetic flux is given by

The average magnetic flux through each turn of the inner solenoid is
Mutual inductance is given by

The mutual inductance of the two solenoids is 
Induced emf is given by

The emf induced in the outer solenoid by the changing current in the inner solenoid is -0.020475 V
Answer:
150m
Explanation:
The relation of speed/time and distance/time is a derivative/integral one, as in speed is the derivative of distance (the faster you go, the faster the distance changes, duh!).
So we need to compute the integral of speed over time from 0.0s to 5.0s.
The easiest way here is to compute the area under the line (it's going to be faster than computing the acceleration and using a formula of distance based on acceleration).
The area under the line is a trapezoid with "height" 5s, and the bases 10m/s and 50m/s. Using the trapezoid area formula of h*(a + b)/2
distance = 5s * (10m/s + 50m/s) / 2 = 5s * 60m/s / 2 = 5s * 30m/s = 150m
Alternatively, we can use the acceleration formula:
a = (50m/s - 10m/s)/5s = 40m/s / 5s = 8m/s^2
distance = v0 * t + a * t^2 / 2 = 10m/s * 5s + 8m/s^2 * (5s)^2 / 2 = 50m + 8m * 25 / 2 = 50m + 100m = 150m.