<h2>Answer:</h2>
<u>Turning a magnet very quickly would be BEST used to create an electric current</u>
<h2>Explanation:</h2>
In Electromagnetic waves electric field produces magnetic field and vice versa. A moving magnet can produce electric current. Dynamo is the best example for it. In dynamo armature is rotated between the magnets which results in the development of electric field and hence an electric current is produced in it.
I think 100 mph pushing the car the opposite direction
The study of sound is called sonics and the study of sound waves are acoustics
624 = 6(7x-1)
104=7x-1
105=7x
x= 15cm
To solve this problem we will apply the concepts related to the Doppler Effect, defined as the change in apparent frequency of a wave produced by the relative movement of the source with respect to its observer. Mathematically it can be written as

Here,
= Frequency of the source
= Speed of the sound
= Speed of source
Now the velocity we have that


Then replacing our values,


Therefore the frequency of the observer is 1047.86Hz