Answer:
527 Hz
Solution:
As per the question:
Beat frequency of the player, 
Frequency of the tuning fork, f = 523 Hz
Now,
The initial frequency can be calculated as:


when

when

But we know that as the length of the flute increases the frequency decreases
Hence, the initial frequency must be 527 Hz
Pitch is the impression the listener gets of the <em>frequency</em> of the sound.
The speed of the sound is <em>not</em> related to its pitch/frequency.
If the speed and frequency were related, that would be a real problem. Bands, orchestras, and choirs could not exist ! All the instruments in the orchestra could play a note together, at the same time. But then the higher instruments ... the flute, trumpet, violins, high guitar strings and high piano keys ... would travel to you fast, and the lower instruments ... the trombone, tuba, double bass, bass drum, low guitar strings and the low piano keys ... would travel to you slow. They all played the note at the same time, but by the time you heard it, it would be all smeared out ... every instrument arriving at your ear at a different time !
Positive Work.
Negative Work.
Case of zero work done.
Displacement at an angle to the force.
Energy.
Kinetic Energy.
work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, it is often represented as the product of force and displacement.