Mechanical disc brakes.
He have a sort of old but not old bike like this one: its a pretty cool bike i love it.
Both, sort of in-between
lies
It most likely means that your brakes are very hot, and that some sort of liquid has touched your brake pads or rotors. Be careful about warping in the rotor.
When the brakes are applied, the car's kinetic energy is converted to heat by friction between the brake pad and the brake disk.
Having Berlin wall attitude is indicative of having a very divisive position on something, probably indicative of some sort of dichotomy.
A little bit of chemical energy from the food that the rider has eaten gets used to pull on the brake lever, the rest is friction. When you pull the brake then a sort of bar comes down onto the wheel. This uses the opposite force of friction to slow you down.
There's usually little advantage to building a bike from scratch, as bike parts are much more expensive bought separately than as a whole package. If you want a mini dirt bike, go buy one. But if you insist, you need all the parts that you'd otherwise find on a bike. An engine, some sort of gearbox and a clutch. sprockets, chain. wheels, rotors, brakes. fuel tank, a fork, a headset THen you need a stack of tubing, tools to miter them, and the tools and skills to make a frame to stick the engine in.
auto braking system they don't stop , they sort of vibrate so you don't skid.
an exercise bike would be the best start
Never heard of any old car that did not have some sort of parking brake.
Probably a religion - "all people are born in sin" sort of attitude.