On the negative post of the battery. Common computer grounds are on the thermostat housing, back of the cylinder head, sometimes on the intake, then main conductors are body to frame, body to battery, body to engine, frame to engine and frame to battery.
The ground wire should come from the ground rod and to the main electrical panel grounding terminal.
In a typical home electrical panel installation the main ground wire is connected directly from a ground rod driven into ground to a dedicated lug on the neutral bus.
Ground bus in the panel.
case of the ground
The rounded third prong goes to earth ground at the main panel where the neutral is also bonded to ground.
It is to prevent electrical shocks.
EarthIts a earth groundat lower potential then your service
The main reason why you should avoid bodily contact with ground while working on live electrical equipment is that such contact will complete a circuit. If you are in contact with any electricity, this means that your body becomes part of the path for the electricity and it will pass through you as it heads into the ground.
The main electrical ground wire is sized to the service and is non insulted bare copper. Branch circuit grounds are green in conduit installations and bare copper again in house wiring cables.
Grounding is an important part of all electrical wiring like your home. Without proper grounding you are asking for all sorts of strange problems and safety issues. The power company provides electricity to your main panel and a good ground is required. This is usually a metal rod in the ground near your meter. This ground is bonded to the main electric panel. The neutral wire is in turn bonded to ground at the main panel. If you have a bad ground, neutral can float above ground causing shock hazards. I once had to chase down a shock problem in a shower. It turned out to be a case where the neutral and ground were not bonded at the main panel. What you shouldn't do is the hot side of power to ground.
Starter solenoid is a part of the starter itself, the ignition relay can be found in the main electrical control panel under the hood.
Yes, it has to be sized to the main circuit feeders to be able to carry the fault current of the main feeders if a fault occurs. Sizing of ground wires for service supplies can be found in the electrical code book. In cable wire sets the ground wire is determined by the manufacturer of the cable.