CHECK OUT THE NEED OF MULTIPLE CYLINDERS IN ENGINE INSTEAD OF A SINGLE BIG ONE OF SAME VOLUME !!

Suppose we have a Chevrolet Spark of 1 litre (998 cc to be exact!) displacement. It has a 4 cylinder engine. So let's see what if we replace it with a single cylinder engine.

Let's do some basic calculations to find out the bore and stroke of this hypothetical engine. Assuming square type of engine ( bore equals stroke) we get bore=stroke=10.9 cm as opposed to original stroke of approx 5.8 cm. ( Assuming stroke of 7.7 cm ) So that is quite a big stroke length! So now let's discuss a few things about this-

1. With this big stroke, we need longer crankshaft. Longer is the crankshaft lesser is the maximum RPM achieved by the engine. This hampers the power output of engine. Hence the single cylinder will never be able to produce the same power as that of multi cylinder for the same compression ratio. Although some might argue that this will fetch good low end torque, which is true.
2. Single cylinders are impossible to balance! They will produce vibrations which are difficult to damp. You will definitely not like your car vibrating like a Royal Enfield bullet. Although flywheels and anti vibration mounts will come to the rescue, but mounts ( not flywheels) require periodic maintenance.
3. You will need to redesign the clutch which was designed to handle smaller bursts of power than a huge single one! Hence the clutch needs to be bigger and stiffer to avoid slipping which will increase clutch pedal effort enormously and break drivers legs. ( Assuming rest remind same). Moreover the transmission gears needs to be reinforced to handle rough shifting. This is not at all good for a nice passenger car!!
4. Single cylinder engines are difficult to keep cool, since the coolant jacket is far from the centre of combustion chamber and piston centre, overheating is more probable.
5. You will be burning all the fuel in one cylinder only which was earlier burnt in four chambers. Complete combustion is difficult to achieve. Also higher in-cylinder temperatures will aggravate NOX formation. Your car is less likely to pass pollution checks unless you invest in expensive Cat-cons. Not at all good for a cheap passenger car.
6. With single cylinder engine your car will start sounding like a oversized Bullet with utterly no respect for refined exhaust note. No one will buy such sounding car.
7. If at all you plan to turbocharge your engine, it will not be recommended by turbo manufacturers for turbo and engine safety. Such huge single cylinder's exhaust putts are capable to destroy a turbines of perfectly matched turbo. Singles are definitely not turbo friendly.
8. Now at this point let's assume you successfully replace the engine overcoming all difficulties. Now there will be such engine parts which you have custom made eg- high Flow fuel injectors, fuel pumps, ECU, also including engine Mechanical parts such as big end bearings and small end bearings etc. But these parts are not even remotely available in any spare parts shop if in case you damage any. If Chevrolet makes such engine they will have to face a lot of difficulties in arranging spares for their angry customers.

CHECK OUT THE REASON FOR LARGER DISC BRAKE AT FRONT AND SMALLER AT REAR !!

As the car brakes, the center of gravity causes a torque (like a big wrench turning the car toward its nose) to force the car to its front tires.

The center of gravity of the car wants to keep going forward. The only thing slowing it down is the transfer of force between the road, and the contact patch of the tire on the road.

That force, which the tire makes with the road, is very simplistic...  That force is composed of only two things. The weight pushing down on the tire, and some number that makes up for the stickiness of the tire, and the terrain it is on.  A sticky tire on good pavement, a high number; a normal tire on ice, a low number. 

Since that force on the tire is highly dependant on the weight on that tire, the amount of braking that the tire can do is directly related to the weight imparted on the tire.

As you can see from the above picture, the front tires can see a bit more weight than the rear under hard braking.

the highest braking capabilities are much higher on the front than on the rear, therefore, we must ensure that those brakes are up to the task.

How do we do that?

Well, it all comes back to torque. Torque is just some force that acts over some distance. It is for this reason that you might use a longer bar on a wrench that you are trying to get a stuck bolt out with.

Let's say you are trying to stop a big heavy tractor tire from spinning. Imagine that you put a little brake pad from the front of a bike a few millimeters from the center of the wheel.  It wouldn't do much would it? Then imagine that you put that same brake, with the same pressure, as far from the center as you could.  Imagine that you could actually put it a few meters farther than the tire. In fact, let's go all the way and say that you could put that little brake pad a few skyscrapers away.  That same little brake pad could do a LOT more to stop that tire.  It would be no problem.

This same principle helps us exert the extra force that we now know front wheels can receive. So bigger diameter brakes up front help even-out the pressure required to stop the car. Those higher forces require additional thickness  to transfer those forces through the disk, and into the hub.

DIFFERENCE BETWEEN EARTHING AND GROUNDING EXPLAINED !!

EARTHING:

1. Earthing means connecting the dead part(the one which does not carry current under normal condition) to the earth(ground). For example electrical equipment frames etc.
2. Under fault condition these parts may attain high potential w.r.t earth(ground) so any living being touching these parts will be subjected to potential difference which may result in flow of current of such a value which may prove to be fatal.

So earthing is to ensure safety or protection of electrical equipment and living being by discharging electrical energy to earth (ground).

GROUNDING:

1. Grounding means connecting the live part(the one which carry current under normal condition) to the earth (ground) for example neutral of transformer, 3- ph star connection etc.
2. Grounding is done for protection of power system equipment and to provide a effective return path from the machine to the power source.
3. During lightening dangerous high voltage can develop in the electrical distribution system wires. Grounding provides a safe return path around the electrical system of your house thus minimizing damage from such occurrences.

Earthing and grounding has a micro difference . So in layman's term we use grounding(earthing) as a common term for both.

Earthing is more common word in commonwealth countries whereas grounding is the word used in North American standards.