1. What is the working principle of hydrostatic propulsion system in a tractor?

It depends on Pascal law. As the pressure in the system is the same, the force that the fluid gives to the surroundings is therefore equal to ‘pressure × area’. In such a way, a small piston feels a small force and a large piston feels a large force

2.What is oil grade SAE stands for?

"SAE" stands for "SOCIETY OF AUTOMOTIVE ENGINEERS" (USA).

3. By mixing oil in fuel of four stroke bike will it damage engine, performance? If not than what happen?

Yes, absolutely. It leads to higher wear and tear in cylinder liners, piston and damage of the piston. It even leads to knocking and detonation where abnormal combustion appears and dark smoke and harsh sound will be produced by the engine.

4. Why are car steering wheels round?

1. A steering wheel is round so that your hands locate in the same place regardless of the steering wheel's orientation. 2. While turning / steering the car it is ergonomically the best design. 3. Also as design is circle, there are no edges to hit while turning / steering is moving as the circle position remains the same. 4. From Design view, it should be able to give uniform force i.e. torque, by varying the distance from center will vary the torque provided.

5. How Trains take turns, though there is no any differential?

Purpose of the differential is to enable vehicles to take turn, by allowing both the wheel to rotate with different speed. This is required when wheels, like in car, are connected with same axle. Interestingly, wheel in trains are not connected with the axle, they are independent and hence can take turns without ant differential. This is same as how the bullock cart takes turns, without any differential.

6. What is the difference between BS2 & BS3 engine?

IN BS2 there is No catalytic converter to reduce formation of co and HC whereas in BS3 catalytic converter is available to reduce the formation of HC and CO. So less emission of HC and co will take place in BS3

7. Why big tyre used in rear of Tractors?

Tractors have big rear tires because, the larger the surface area of the tractor's wheels touching the ground, the more pulling power you have. Like how tractor pullers have large tires. Another reason is that the tractor doesn't have to operate at a higher speed to get the same ground speed with larger tires. Gear ratios don't have to be as high b/c of the larger tires.

8. What will happen if someone adds oil to the fuel of four stroke bike engine?

This will result in damaging of the engine faster. Adding oil will lead to the higher wear and tear of the cylinder liner, piston and damage to the piston. It will lead to abnormal combustion and knocking and detonation. Dark smoke and abnormal sounds will be generated by the engine. One should not mix oil with the fuel of four stroke engine.

9. How air conditioners work in cars?

Air conditioners are based on the principles of evaporation and condensation and then compression and expansion. The hot air of the car is removed by the process of evaporation and then the condensation of the evaporated air takes places which is then further compressed by the compressor and then finally expanded to us in the form of cold breeze. Somehow, Air conditioning reduces the average of the car, as the energy is required to remove the hot air and then compression and expansion.

10. Why entropy decreases with the increase in temperature?

The relation is ds = dQ/T Entropy is inversely proportional to the temperature so as temperature increases, entropy decreases.