Pulsating Brakes

When I press on the brake pedal there is a pulsating feeling on the pedal. Then when I come to a complete stop, there is a slight grinding sound. I think that the rotor maybe warped on the front left wheel. Would anything else cause this behavior? I'm going to swap the left rotor with the right one to see if the problem is still there.

Rotors cost between twenty and thirty dollars for you car. Common causes for the rotor to warp are using air guns to install wheels. Grinding noise can be caused by worn pads.

Ok thanks