Brake grinding

Hey all. Not sure if this is the right forum, but I'm hearing a strange niose from my right/rear wheel area.
It only occurs when I braking, so I assume it's the rotors or something. It sounds as if there is some crud on the rotor, because you can hear the grinding with a "frequency": it occurs faster when the wheels are going faster, and slows down with the car.

Any ideas?
Also, what are good ways to clean crap off the brake assembly?

 

do u have enough pad left?

 

I've only had the car for about 5,000 miles. I've never braked hard. So I assume I have enough of everything left.

 

i'd check the pad first and see if its spent

 

k

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