With some difficulty. For the most common design you will need a set of special tools called cone wrenches. With a cone wrench to hold the cone you can use a normal wrench to undo the locknut, and with that one out of the way you can pull the cone after which the axle will slip right out. As the axle comes out, so will the ball bearings - so do this over a bucket or something.
Do note that different designs require different methods. Internally geared hubs for instance will require more than what's described above.
See links for more.
A bicycle is both.
Simple machines are things that change the direction or magnitude of a force. A bicycle saddle doesn't do that, so no.
Wheel and axle.
a bicycle
No it is a compound machine, seach "bicycle" and "compound machine" on google to verify.a bicycle is a compound machine. it has a wheel and axle and levers. the wheel and axle is the wheel of course, and the lever is the handle bars a bicycle is a compound machine. it has a wheel and axle and levers. the wheel and axle is the wheel of course, and the lever is the handle bars a bicycle is a compound machine. it has a wheel and axle and levers. the wheel and axle is the wheel of course, and the lever is the handle barsbi cycle is not a simple machine
wheel and axle, and the lever.
a bicycle an automobile a go-cart
Wheel-and-axle, levers, inclined planes.
steering wheeltire wheelsA wagon
gears and wheel and axle
a bicycle an automobile a go-cart
Rust (oxidation of metal) is a chemical change but it is also a physical change in the strength of the material.