The radio waves are electromagnetic wave, so it travels with velocity of light i.e .
We can use the relation between frequency, wavelength and speed as
Here c is speed of light, is wavelength and f is frequency and its value is given 99.90 FM, it is actually in megahertz (i.e 99.90 MHz).
Therefore,
.
Thus, the broadcast wavelength of the given radio station is 3.003 m.
The work done is 375 J
Explanation:
The work done by a force in moving an object is given by
where
F is the magnitude of the force
d is the displacement
is the angle between the direction of the force and the displacement
In this problem,
F = 75 N is the force applied to the couch
d = 5 m is the displacement
Assuming the force applied to the couch is parallel to the motion,
And so, the work done is
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