The same formulae that we saw already are applicable here too. Here we shall see some examples of this concept and then learn some tricks from other examples. It crosses a certain pole that is in the way in 9 seconds. What is the length of the train? Answer: The train crosses the pole in 9 seconds.
This means that from the point when the engine or the front of the train crosses the pole to the point when the back of the train reaches the pole, we have 9 seconds. Thus we can get the length of the train by calculating the distance that the train travels in 9 seconds. Let us do it for the current example. Therefore the correct option is D meters. Let us see some more examples that can be formulated on the basis of this concept.
Example 2: A certain train is m long. It takes the train 10 seconds to cross the man completely. Then the speed of the train is:. Answer: Here we will have to use the concept of the relative speed. The relative speed of two objects is the sum of their individual speeds if they are moving opposite to each other.
Practical Rules for the Management of a Locomotive Engine - in the Station, on the Road, and in cases of Accident [Charles Hutton Gregory] on swagboriterne.gq Author, Gregory, Charles Hutton, Title, Practical Rules for the Management of a Locomotive Engine in the Station, on the Road, and.
If the two objects are moving in the same direction, then their relative speed is equal to the difference between the two speeds. The ratio of their speeds is:. Hence the correct option here is B In what time will it pass a bridge m long? In how much time will the train pass the jogger? Their lengths are 1. The time taken by the slower train to cross the faster train in seconds is:. The faster train passes the slower train in 36 seconds. The length of each train is:.
LIterally contradict yourself by saying distance is greater than or equal to displacement then saying that displacement can never be less than distance but if distance is greater than or equal to then displacement would be less than or equal too sick contradiction. The book is just as entertaining today as it was when I was nine. Large yards may have a control tower. The start of vaporisation causes a delay before ignition and the characteristic diesel knocking sound as the vapour reaches ignition temperature and causes an abrupt increase in pressure above the piston not shown on the P-V indicator diagram. The time taken by the slower train to cross the faster train in seconds is:.
LIterally contradict yourself by saying distance is greater than or equal to displacement then saying that displacement can never be less than distance but if distance is greater than or equal to then displacement would be less than or equal too sick contradiction. Many of your questions are wrong let alone solutions. Diesel was attacked and criticised over a time period of several years. Critics have claimed that Diesel never invented a new motor and that the invention of the diesel engine is fraud. His claims were unfounded and he lost a patent lawsuit against Diesel.
Diesel sought out firms and factories that would build his engine. On 10 August , the first ignition took place, the fuel used was petrol. Between 8 November and 20 December , the second prototype had successfully covered over hours on the test bench. In the January report, this was considered a success.
In February , Diesel considered supercharging the third prototype. During summer that year the engine was built, it was completed on 6 October The engine was rated The characteristics of a diesel engine are . The diesel internal combustion engine differs from the gasoline powered Otto cycle by using highly compressed hot air to ignite the fuel rather than using a spark plug compression ignition rather than spark ignition.
In the diesel engine, only air is initially introduced into the combustion chamber. The air is then compressed with a compression ratio typically between and This high compression causes the temperature of the air to rise.
At about the top of the compression stroke, fuel is injected directly into the compressed air in the combustion chamber. This may be into a typically toroidal void in the top of the piston or a pre-chamber depending upon the design of the engine. The fuel injector ensures that the fuel is broken down into small droplets, and that the fuel is distributed evenly.
The heat of the compressed air vaporises fuel from the surface of the droplets. The vapour is then ignited by the heat from the compressed air in the combustion chamber, the droplets continue to vaporise from their surfaces and burn, getting smaller, until all the fuel in the droplets has been burnt. Combustion occurs at a substantially constant pressure during the initial part of the power stroke. The start of vaporisation causes a delay before ignition and the characteristic diesel knocking sound as the vapour reaches ignition temperature and causes an abrupt increase in pressure above the piston not shown on the P-V indicator diagram.
When combustion is complete the combustion gases expand as the piston descends further; the high pressure in the cylinder drives the piston downward, supplying power to the crankshaft. As well as the high level of compression allowing combustion to take place without a separate ignition system, a high compression ratio greatly increases the engine's efficiency. Increasing the compression ratio in a spark-ignition engine where fuel and air are mixed before entry to the cylinder is limited by the need to prevent damaging pre-ignition.
Since only air is compressed in a diesel engine, and fuel is not introduced into the cylinder until shortly before top dead centre TDC , premature detonation is not a problem and compression ratios are much higher. The p—V diagram is a simplified and idealised representation of the events involved in a diesel engine cycle, arranged to illustrate the similarity with a Carnot cycle. Starting at 1, the piston is at bottom dead centre and both valves are closed at the start of the compression stroke; the cylinder contains air at atmospheric pressure.
This is only approximately true since there will be some heat exchange with the cylinder walls. During this compression, the volume is reduced, the pressure and temperature both rise. At or slightly before 2 TDC fuel is injected and burns in the compressed hot air.
Chemical energy is released and this constitutes an injection of thermal energy heat into the compressed gas. Combustion and heating occur between 2 and 3. In this interval the pressure remains constant since the piston descends, and the volume increases; the temperature rises as a consequence of the energy of combustion.
At 3 fuel injection and combustion are complete, and the cylinder contains gas at a higher temperature than at 2. Between 3 and 4 this hot gas expands, again approximately adiabatically. Work is done on the system to which the engine is connected. During this expansion phase the volume of the gas rises, and its temperature and pressure both fall. At 4 the exhaust valve opens, and the pressure falls abruptly to atmospheric approximately. This is unresisted expansion and no useful work is done by it.
Ideally the adiabatic expansion should continue, extending the line 3—4 to the right until the pressure falls to that of the surrounding air, but the loss of efficiency caused by this unresisted expansion is justified by the practical difficulties involved in recovering it the engine would have to be much larger. After the opening of the exhaust valve, the exhaust stroke follows, but this and the following induction stroke are not shown on the diagram.
If shown, they would be represented by a low-pressure loop at the bottom of the diagram. At 1 it is assumed that the exhaust and induction strokes have been completed, and the cylinder is again filled with air. Work output is done by the piston-cylinder combination between 2 and 4. The difference between these two increments of work is the indicated work output per cycle, and is represented by the area enclosed by the p—V loop. The adiabatic expansion is in a higher pressure range than that of the compression because the gas in the cylinder is hotter during expansion than during compression.
It is for this reason that the loop has a finite area, and the net output of work during a cycle is positive. Due to its high compression ratio, the diesel engine has a high efficiency, and the lack of a throttle valve means that the charge-exchange losses are fairly low, resulting in a low specific fuel consumption, especially in medium and low load situations. This makes the diesel engine very economical. In his essay Theory and Construction of a Rational Heat Motor , Rudolf Diesel describes that the effective efficiency of the diesel engine would be in between Diesel engines rely on internal mixture formation,  which means that they require a fuel injection system.