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Mechanical Engineering
Mechanical Engineering is a branch of engineering that encompasses the generation and application of heat and mechanical power and the design, production, and use of machines and tools. Mechanical engineering involves application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, materials science, electronics, and mathematics.
10,989 Questions
Let's say that you take a plastic 1-liter soda bottle, empty out the soft drink it contains, put the cap back on it (so you have a sealed bottle full of air), tie a string around it like you would a balloon, and dive down to the bottom of the deep end of a swimming pool with it. Since the bottle is full of air, you can imagine it will have a strong desire to rise to the surface. You can sit on the bottom of the pool with it, holding the string, and it will act just like a helium balloon does in air. If you let go of the string the bottle will quickly rise to the surface of the water.
The reason that this soda bottle "balloon" wants to rise in the water is because water is a fluid and the 1-liter bottle is displacing one liter of that fluid. The bottle and the air in it weigh perhaps an ounce at most (1 liter of air weighs about a gram, and the bottle is very light as well). The liter of water it displaces, however, weights about 1,000 grams (2.2 pounds or so). Because the weight of the bottle and its air is less than the weight of the water it displaces, the bottle floats. This is the law of buoyancy.
Another way is the way a hot air balloon works. Put a gas fire almost in the balloon. The fire puts really hot air in the balloon. The material the balloon is made of keeps the hot air in. the balloon rises because hot rises. the temperature must be a certain amount higher then the air out side depending on the load.
Difference between steady state and transient analysis?
In steady state analysis, you assume anything that changes with time is 0. ie: d*rho/dt = 0. In transient, you keep all your d/dt terms. Steady state simplification is a handy tool to make many differential equations solvable, by reducing their "dimension", as x-direction, y-direction, z-direction, and time are each dimensions.
A short piece of solid bar steel used when jointing 2 pieces of tubing. The tubes are slid over the slug, to reinforce the joint and it adds additional metal to weld too.
When a newly manufactured pressure vessel is to be certified from ASME AI (Authorized Inspector), the AI stamps a form called "ASME U1A Form" with signature certifying that the vessel fabrication has been done according to the rules laid down by ASME Section VIII.
What happened in steam turbine if governor failed in open position?
It could overspeed and wreck itself-but there are emergency stop valves as well as the governor, so it is unlikely.
What is the difference between an slide gate and a sluice gate valve?
The difference is that a sluice gate is made out of cast iron while a slide gate isn't.
What are examples of dynamic and static loading of bones?
Dynamic means moving...so doing bicep curls would be an example.
Static means being still or holding what you have.So when you stand erect your back/spine and legs are in a static posture.
Learn more about how static and dynamic postures can cause carpal tunnel syndrome athttp://www.carpal-tunnel-symptoms.com
it is possible that you fridge may be a look alike. however, some stainless steel fridges do attract magnets, but you would need a stronger magnet then just an average kids type of alphabet magnet. hope this helps :)
Why is aircraft skin by rivet rather than weld?
Aircraft skin is made from an aluminum alloy material, often coated with pure aluminum to resist corrosion.
Welding is a process that uses electrical current to melt the base metal to form a continuous joint in usually ferrous (iron) materials. Whilst it is possible to weld aluminum it is not used for the following reasons:
1.Heating aluminum alloys causes them to take on a hardness which would then need to be removed by further heat treatment. It's hard to put a whole aircraft into an oven to heat it to 300C to anneal it.. there are no ovens that big.
2. A weld is stiffer than the surrounding material. It would therefore be prone to crack. If you want to sit in a tin can at 10,000M when that weld opens that's up to you.
3. The surface corrosion protection of the pure aluminum would also be lost in the heat of the weld.
4. Rivets are reliable, strong and easily removed and replaced in case of repair.
Welds are an unreliable method of joining materials, they cause oxidation and heat damage. They cause inclusions which can cause cracks and corrosion and all welds are variable in terms of depth and strength, even when made by machine.
Not for aircraft!
What is a overhead bridge crane?
Gantry cranes are a type of crane built atop a gantry, which is a structure used to straddle an object or workspace. They are also called portal cranes, the "portal" being the empty space straddled by the gantry.
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The terms gantry crane and overhead crane are often used interchangeably, as both types of crane straddle their workload. The usual distinction drawn between the two is that with gantry cranes, the entire structure is usually wheeled. By contrast, the supporting structure of an overhead crane is fixed in location, often in the form of the walls or ceiling of a building, to which is attached a movable hoist running overhead along a rail or beam. Further confusing the issue is that gantry cranes may also incorporate a movable beam-mounted hoist in addition to the entire structure being wheeled, and some overhead cranes are suspended from a freestanding gantry.
Why you used Alternating current in gas tungsten arc welding?
A couple primary reasons. 1 the current reversing itself helps to break up oxides on the surface of the metal. 2 Alternating current produces more heat in the arc which is useful in welding aluminum because heat dissipation is rapid in this metal.
Ans: In brief, A106 is a ASTM standard code for carbon steel tubing/ piping material.
Gr B at the end is mean for its thickness grade. It have A, B, C.
Gr.B tubing/ piping is almost equal to SCH 40 piping material.
Should this question be?
= What is the volume of 1 cu ft of water vapor at 100 degrees F and atmospheric pressure? =
It's initial volume doesn't matter as you only want to know what its final volume is.
How do servo motors alter the RPM?
servo motors change their rpm as instructed
servo motors recieve instructions from a controller to do some action
servo motors generally have feedback so the controller can see where they need to go
servo motors can be electric air or hydrolic powered
an example:
cars have a cruse control
you set a desired speed of travel
the vacuum powered servo motor controls the throttle of the gas engine
the transmission controls the ratio of gearing so the engine is not overloaded
at some point when conditions are satisified you will get the correct speed ...
if you go over the desired speed the vacuum powered servo motor backs off
which eventually controls the differential driving rpm of the rear wheels
here again the servo motor can be considered to be the valve on the vacuum bladder or the entire drive train
Why draft tube is used in francis and kaplan turbine and not in pelton turbine?
The Kaplan turbine is a newer, more revolutionary version of the Francis turbine, which came before it. The draft tube is used so that the turbine does not need to be where the water flow is lowest.
A compression shock wave will travel back into the liquid at the speed of sound. In domestic water systems this is called "hammer".
What is the power source for a hovercraft?
Use a vaccum or a leafblower to power a hovercraft. You need a powerful vaccum or leafblower oif you use one! : ) You can also use a giant fan.
The question, "Describe a situation in which you have used a creative solution to solve a problem", is commonly asked in interviews for jobs or entrance into higher institutions of education.
Most of us feel challenged to come up with a fantastic answer! How did I alone save the world? But, employers and educators don't want the most fantastic story; instead, they want to hear (1) how you think about problems (2) how you initiate solutions to problems and (3) your skills with implementing the solution you came up with. It doesn't matter if your solution worked-- it's more about the process involved!
Some very simple examples:
- Customers in a convenience store were always leaving their original documents in the ten-cent-for-fee copying machine. Customers would come back to get their originals, only to find another customer removed the papers from the copying area, or had thrown them away. SOLUTION: When each customer came to the cashier to pay, the cashier counted the originals AND the copies, before charging for the copies. The cashier could then politely say, "It seems all of your originals are here; please check through them before leaving the store. SOLUTION 2: An employee made a sign with bright lettering, "Remove your originals when finished. Originals left behind will be shredded in 24 hours."
- An employee at a grocery store noted that many people read magazines while waiting at the front desk, but never bought the copy. He suggested to the owner to move the magazines for purchase to a different area, and to keep several out-of-date, previously-read, magazines near the counter for use while waiting in line.
- An office kept printer ink on a high shelf. The boxes of copier paper sat in front of the shelves. Although ink wasn't needed that often, a couple times the solution spilled on the opened copier paper box, wasting the ink and ruining the paper. SOLUTION: The secretary suggested moving the copier paper to the opposite side of the copier, and closer to where it is loaded. She also suggested that the copier ink containers be moved to a waist-high shelf to avoid having to reach above the head. There were no more spills and no more ruined ink.
- At home, a mom dropped her ring down the drain and thought it was gone. But her son knew that it could be caught in the "trap" in the pipe. He told his mom not to run the water. When dad got home, he took the pipe apart and the ring was found in the trap.
A "problem" does not need to be a critical problem. It can be an ordinary, every day problem that occurs. The solution does not need to be complex. It needs to be logical, creative, or thinking.
I don't understand the question. It would appear that you wish to compare a centrifugal compressor and an axial flow compressor operating at the same speed and delivering equal flow rates. What is the process fluid? What is the question? Is the "equal air flow" the mass flow rate? At what pressure differential would you like to consider these machines? What is it that you wish to compare? Is it weight, frontal area, mechanical efficiency, overall diameter, length, delivery temperature, input power or what?
What is centrifugal coupled pump?
You may mean a "close-coupled pump" in which case, that is a pump which is mounted directly on the same shaft as the driving motor: i.e. there is no baseplate or coupling to join the two shafts, drive and driven, and the pump hangs off the notor frame. A centrifugal pump is a type of pump where the liquid is forced to travel by an impeller which is inside a close-fitting chamber, or "volute" - it is probably the most common industrial and domestic pump type.
What are the Advantages of reciprocating pumps?
A reciprocating pump is basically a piston in a cylinder with 2 check valves in ports in front of the piston. When the piston is moving back in the cylinder, a check valve allows fluid to fill the cylinder from the intake port, while the discharge port is blocked by its check valve. When the piston goes back the other way, the check valve in the discharge port allows fluid to pass while the check valve in the intake port closes.
