Hyundai Repair: Brake and whining noise, rear brakes, master cylinder

Question
1.  When I accelerate the brake light has started to come on - not all the time however.
2.  When I accelerate and turn (mostly right) there is a whining noise.

Answer
Sounds like either the front or rear brakes (or both) are worn.

When the pads wear, the fluid in the master cylinder is displaced to the calipers, causing the low fluid sensor in the master cylinder to activate the brake warning lamp.

Most cars now also have brake pad wear indicators. When the pads wear down, they rub the rotors and make a squealing or whining noise when the vehicle is moving.  This is intended to provide you advance notice prior to damaging the rotors.