Nothing much happens. The music keeps playing.
Stereos use electricity, probably generated by burning fossil fuels. Someone pays the electricity bills. Turning it off at the wall when nobody is listening will save money and energy. This is good for everyone.
The stereo will begin to heat up thus causing a small potential fire in the back on the stereo unit. It will then begin to travel down the fuel lines and into the engine, where an explosion will promptly occur. This may cause death to near-by lifeforms.
There will be no music.
Leave your doors unlocked :)
Nothing happens. The stereo has a transformer that converts the power to DC, and 50 or 60 Hz input makes no difference.
Leaving a stereo system all the time will likely cause no issues. Most modern stereo systems are 100 percent solid state and are not overly affected by heat.
Stereo can't work unless sufficient voltage , same will be connected to higher input voltage your system will be damaged.
Nothing.
Put it in your car, turn it on and see what happens.
Many things can happen when your stereo is on for too long. If batteries are being used they will die from the stereo being left on. If the stereo is plugged into the outlet then the electric bill can be run up and there is a possibility that it will become too much for the power source and blow a fuse.
Leave the vehicle parked in a bad neighborhood with the doors unlocked.
it gets peed on!
i usually leave lotion on my face overnight and nothing happens so ur good