This is normal. Average braking causes friction which causes heat but, excessive heat from one rotor could be caused by a sticky or stuck brake caliper.
Most common cause is imperfection in rotor or rotor's. Rust or hot spots.
Friction. The brake pads clamping on the rotor creates friction which creates heat.
They get hot because of friction between the rotor (the disk part or the brake system), and the brake pads. (the pads that clamp on the rotor to create friction to slow the vehicle.
The friction between the brake pad and rotor produces heat. That heat will make the lugnuts hot.The friction between the brake pad and rotor produces heat. That heat will make the lugnuts hot.
bad cap or rotor first thing to check
When your rotor warpes it means that it has a wobble in it! From factory they come straight. they usually get warped when they get to hot or a rock gets up there and bends it. If it is really bad it could cause totall break loss!
Brake pads normally yet hot under normal use. The brake pads will get excessively hot if they are not adjusted properly. The wrong brake pads can be too thick and might be rubbing on the rotor.
When a large turbine rotor stops it will still be hot and will tend to bend in the middle if left to cool normally. To prevent this the barring gear will turn the rotor slightly at given intervals during the cool down period.
There could be several reasons such as, you forgot to release the e-brake and drove the vehicle with the e-brake on, or a grease seal went bad and grease is getting onto the hot brake drum or brake rotor, or brake fluid from a leaky wheel cylinder or caliper is getting onto the hot brake drum or brake rotor.
You have to heat up the contact points the rotor around the studs with MAP gas then try hit it but if that doesent work then you need a torch (MAP and oxgen) to get it red hot.
Because there is no current flowing in the rotor, and thus there is no magnetic field in the rotor, and thus there is no torque between the rotor and the field.
What is a rotor?