Which of the following frequencies falls in the range of rf waves used by commercial radio broadcasting stations?

a. 6,000 hz
b. 6,000,000 hz
c. 60 hz
d. 600,000 hz

A).  6,000 Hz.
No.  This is in the middle of the human hearing range.  If a radio station were transmitting on this frequency, then every wire and cable in town would pick up a little of its energy, and you'd hear it on every telephone, earbud, and headphone, and it would come out of every loudspeaker.

B).  6,000,000 Hz.  (6 mHz)
No.  This isn't used by 'commercial' broadcasting stations, but it IS used by
foreign short-wave stations, to broadcast news, 'culture', and propaganda
into other countries. 

C).  60 Hz.
No.  This is the frequency of the AC that you use when you plug anything
into a wall socket.  All of the electric company's power lines RADIATE a
little bit of energy at this frequency, so it wouldn't be a very smart frequency
for a radio station to try to use, since the whole country is already blanketed
with interference at this frequency.

D).  600,000 Hz  (600 kHz)
Yes !  This is the "600" or "60" or "6" that's marked
near the left end of your AM radio dial.
yay !

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.

Answertraveling around a circular trackexplanation"traveling around a circular track" is the best answer as you could be traveling around a circular track at a constant speed. your velocity would therefore have the same magnitude but will always be constantly direction. since acceleration is the rate of change of velocity, the rate of change will only involve the direction of velocity and not the magnitude.wrong choices: "an object at rest" does not accelerate at all"increasing speed while traveling around a curve" means that the acceleration will not be constant due to only change in direction; it will be constant due to both magnitude and direction"an object in free fall" does not necessarily change direction