Mechanical Engineering Interview Questions and Answers
Question - 11 : - Why Do The Radiators In Your House Click When You Start The Heating System?
Answer - 11 : - They are clicking because they are heating up. The heat causes expansion and that is why you hear clicking.
Question - 12 : - How Can I See Where Pipes Are Behind The Wall?
Answer - 12 : - By using radio waves.
Question - 13 : - How Are The Pneumatic System And The Hydraulic System Similar?
Answer - 13 : - Pneumatics use gases such as air or nitrogen, hydraulics use oil or water, both systems use pressure to act on a specific application.
Question - 14 : - What Is The Difference Between An Electric Motor And An Electric Generator?
Answer - 14 : -
There is no fundamental difference between an electric motor and an electric generator or dynamo. In normal use, all motors behave as generators, and all generators behave as motors. DC Motors act like generators because they use less electrical energy when allowed to spin fast. DC generators act like motors because they become easier to spin when less electrical energy is drawn from their terminals.
For example, connect two small DC magnet motors together. Then if you spin the shaft of the first motor, the second motor's shaft will start spinning too. One acts as a DC generator, and the other acts as a DC motor. Alternatively, spin the second one's shaft, and the first one will start spinning.
Another example: If you connect a small DC motor to a small battery, then an electric current will appear in the motor's coils, and the motor starts spinning. However, if you spin the motor's shaft slightly faster than the normal speed, the direction of current in the circuit will reverse, and the battery starts taking in energy from the motor. The motor has become a generator, and it is recharging the battery.
Question - 15 : - What Are Some Examples Of A Periscope?
Answer - 15 : - It is an optical instrument for viewing objects, which are above the level of direct sight; mostly used in submarines.
Question - 16 : - What Does Green Field Project Mean?
Answer - 16 : - Green field projects are those projects, which do not create any environmental nuisance (pollution), follows environmental management system and EIA (environment impact assessment). These projects are usually of big magnitude.
Question - 17 : - Is Pipe Round Because It Provides The Least Area To Volume Ratio?
Answer - 17 : -
More likely because it is easier to manufacture, much easier to put threads on, you do not have to worry about orientation when you put them together, and they have no weak spots created by corners.
My gutter pipes are rectangular because they do not stick out as far from the house as a circular one with the same area. However, they are low enough in the pressure they contain that they can be formed from sheet metal with a crimped seam. Making a water supply pipe, that way would be impossible.
In addition, it is easy to keep them aligned to the house. Running a rectangular water main under a street would be a major pain.
Question - 18 : - Who Built The Trans Alaska Pipelene?
Answer - 18 : - The pipe was constructed in six sections by five different contractors employing 21,000 people at the peak of work.
Question - 19 : - How Is A Submarine Able To Submerge And Surface?
Answer - 19 : -
Submarines have ballast tanks. The tanks can hold air, or they can be "vented" and water can flow into them and fill them completely. When the tanks are full of air, the submarine is buoyant and floats. When the main vents are opened, the tanks are flooded and the submarine submerges. When the submarine is submerged, wants to surface, air can be injected at high pressure into the ballast tanks to force out water, again make the submarine buoyant, and cause it to rise to the surface and float.
In practice, when a submarine surfaces, it doesn't use a lot of air from its high pressure air tanks to "blow the ballast tanks" because it takes a long time to pump up the high pressure air tanks again. What happens is that all the ballast tanks are given a "good shot" of high-pressure air (a few seconds), and then the planes are used in conjunction with the screw (which some call a propellor) to actually drive a submarine to the surface. Once there, something called a low-pressure blower system can be used to finish blowing the ballast tanks (while the high-pressure air compressors are running to pump the high-pressure air tanks back up).
Question - 20 : - What Is Railroad Track Ballast?
Answer - 20 : -
That being said railroad track ballast is the cover for the subgrade. Ballast has several functions:
- It enables water to drain from the track.
- It assists in helping control the thermal expansion of continues welded rail.
- As a train passes the rails, it supports the train.
- It distributes the weight of the train from the track structure to the sub grade.
- Maintains a smooth running surface for the train to run on.
As ballast becomes contaminated with other materials, it looses its ability to do some or all of these jobs.