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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
Tensile strength is the capacity to resist tension; in other words, if you pull on both ends of an object (typically a wire), the tensile strength tells us how much force it can withstand before it snaps into two pieces.
How much force is required to crush an aluminum beverage can?
I was thinking about a standard 12oz aluminum beverage can. Dimensions in inches: Outer diameter = 2.6, Inner diameter=2.53, thickness=0.035, height of can=4.8 I don't think Euler's buckling formula is valid here, because the slenderness ratio of the can is not large enough. I did some experiments, by placing can on bathroom scale and slowly applying force with my foot. Most cans crush when the scale reaches 100 to 120 lbs, but I've had some as high as 180, and as low as 80. Does this sound reasonable?
What devices do scientist use to measure things?
Thermometer for temperature; or temperature probe;
measuring cylinder, burette, pipette for volume;
electronic balance for mass;
pH probe for acidity;
spectrophotometer for colour wavelength;
mass spectrometer for relative mass
The list is endless.
What is cooling tower fogging?
cooling tower cleaning is required when the actual approach temp is significantly higher than the design. this may be due to fouling of spray nozzles of water distribution system and or fouling of fills media specially in film fill type cooling towers. This fouling materials is mainly consist of biofilms, calcium salts trapped in biofilm, dust & dirt. on line chemical cleaning followed by a good scale cum dispersant chemicals are required to control any further fouling of the cooling tower in future. Bashist Kumar Vasu chemicals
Nitrates are formed by the chemical bonding of Nitrogen and 3 Oxygens, yielding the anionic formula NO3-. This can be caused by a variety of chemical reactions involving nitrogen and oxygen where the environment is favorable for forming a nitrate ion or compound.
You know 0.02 BTU is needed to raise 1 cu ft of air 1 degree Fahrenheit But how long does it take?
Thanks for the answer. I need to rephrase my question. I have a source of energy, creating heat at the rate of 6000BTU/hour in a room. What to know how long does it take the room temprature changes from 86F to 96F
New Answer:
You have the heat input rate (6000 BTU/hr) and you know the size of the room. I don't know this last fact, so the answer will be "plug in your values". Also I assume heat can be distributed very quickly
Volume of Room: HxWxL
Volume of air in room = Volume of room - Volume of furniture (assume 800 ft3)
Hourly heating rate in ideal conditions =
0.02 BTU/hr x 1 ft3 = 1o F/hr
0.02 BTU/hr x 800 ft3 = (1/800)o F/hr
1 BTU/hr x 800 ft3 = (50/800)o F/hr = 0.062o F/hr
6000 BTU/hr x 800 ft3 = (6000 x 0.062)o F/hr = 372o F/hr
Assume heating rate is proportional to how long the heater is on (actually a bit off because air is cooled by walls and furniture etc.)
For a 800 ft3 room the heater would heat the room 10o F in (10/372) hrs, about (1.5 minutes. For larger or smaller rooms the time would be
(1.5 minutes) x 800/(Actual room volume) = Time to raise temperature by 10o F
--------------- Rate of temperature change is dependent on how rapidly the energy is supplies. Consder to 1 ft3 boxes of air, insulated so that no heat can enter or leave.
In the first box we introduce a small amount of gaseous explosive that will release 0.02 BTU of heat when ignited. In the second a finely divided iron powder that floats in the air and slowly rusts releasing the same amount of energy. The explosion and rusting are allowed to happen. Both boxes now contain air 1o F warmer than the initial condition. One box acheived the change almost instantaneously, the other over the course of hours or days.
In real life situations the heat is transferred through the box by convection and conduction. The rate depends on the temperature of the heater and the amount of agitation of the air.
What is the tensile strength of uranium?
The density of uranium is 19,1 g/cm3 and the hardness is 6 on the Mohs scale.
Why is the exhaust mounted to the vehicle by flexible joint?
Thermal expansion.
An exhaust pipe gets up to 600 degrees or more. The coefficient of expansion of steel is 8 millionths of an inch per inch per degree. a 12 foot exhaust increasing (and decreasing) in temperature by 500 degrees will expand overall a little more than 1/2 inch. If the pipe were mounted solidly the mounting bracket would eventually break, or the pipe would break, from the strain put on it by the expansion.
What is the equivalent BS steel of astm a36 steel?
BSEN 10025-3GRS420N give me the material composition number
How much money does a drilling engineer earn?
. Actually, I am studying to become a drilling engineer, average starting salary is between 90,000 and 110,000. This is depending on many things such as your school attended, job applied for etc. You should expect to make a good 3,000 a week. And with about 5 years experience, expect to make 150-180k per year. The downside in the drilling business is being on call 24 hours and it is very sensitive to the capital spending cycle in the oilpatch.
What are the different types of Turbines used in hydroelectric power plants?
1 Pelton Turbine
2 Kaplan Turbine
3 Francis Turbine
4 Propeller Turbine
5 Tubular Turbine
A simple windmill consists of a vertical post with two rotating hubs - one vertical, one horizontal - attached at the top. Each hub is attached to the other, allowing the windmill to rotate horizontally and point into the wind. The vertical hub has slats attached radially to it, each one at a slight angle. As the wind passes over the slats, the Bernoulli principle (high pressure/low pressure) causes the vertical hub to rotate. By itself, a windmill is just decorative, but if big enough, it can be used to rotate grist stones in mills, run pumps, etc.
What are the dangers of underwater welding?
because when you strike an arc underwater, the light attracts sharks, and then they eat you.
What is the difference between left-hand thread and right-hand thread?
The difference between left- and right-hand thread is that one is turned in a given direction to tighten the fastener, and the other is turned in the opposite direction to tighten the fastener. Let's look a bit more closely.
Most fasteners with threads are turned clockwise to tighten them. (This is true for a nut, and for a bolt, you'd be looking at the head with the threads away from you.) These are right-hand threaded fasteners. These fasteners are turned counter-clockwise to loosen them, as you might have guessed. With left-hand fasteners just the opposite is true when tightening them or loosening them.
We make left hand fasteners for special purposes. We'd have to have a reason to make "backwards" threads on a fastener, wouldn't we? We do, and most applications where we see left-hand threaded fasteners involve attaching rotating parts. A lawn mower blade is a good example, and by looking at the physics, it will become obvious.
A lot of blades on lawn mowers attach to the shaft of the motor with a nut or a bolt. You know the machine we're talking about. The motor shaft points straight down, and the blade is a "cutter bar" with the ends sharpened. Anyway, if the motor on the machine turns clockwise (looking at the motor from the bottom where the blade is attached), using a fastener that turns clockwise to tighten it (a right-hand threaded fastener) sets the stage for a problem. Roll up your sleeves and look at the physics.
When the motor starts, it "torques" the shaft clockwise. The blade and the fastener that hold the blade are likewise torqued clockwise. But consider mean old inertia. Inertia is the name we give to the phenomenon associated with objects that have mass (like the fastener that holds the blade on). If a body is at rest, it wants to remain at rest. If it's in motion, it wants to remain in motion. Force is necessary to change the motion of a mass because of inertia. That said, let's focus on the bolt that holds the blade on the motor.
If the bolt on the motor shaft of a lawn mower turns clockwise and a right-hand threaded bolt holds the blade on, the inertia of the bolt when it's at rest makes it "resist" the torque of the motor, which is clockwise. The effect on the bolt is that the bolt's inertia makes it want to turn counter-clockwise. And counter-clockwise is the direction we'd turn the fastener to take it off. If the motor is started time and time again, it applies a little torque in the "wrong" direction to the bolt that holds the blade on. If the bolt ever becomes a bit loose, it can easily be spun off, which will cause the blade to detach. If the blade comes off while the machine is running at speed, that blade becomes a lethal projectile.
Left-hand threads are applied in a number of applications, and most involve rotating parts. It costs more to make left-hand threaded fasteners because the volume in which they are produced is lower. The economy of scale makes the right-hand threaded fasteners cheaper, and they would be a manufacturers choice if not for the engineering considerations associated with the rotating parts of a machine. Left-hand threaded fasteners are made for a specific application where right-hand threaded fasteners would be a fool's choice.
How do you convert refrigeration tons to BTU?
This conversion is very simple : and is 1 ton = 12,000 BTU/hour.
So if you have a 3 ton of refrigeration you have 36,000 BTU/hour.
In addition, I want to add that in some large Data Centers, there is a movement from BTU to kW of power used by equipment. This is probably driving the Tons/kW question that the HVAC engineers are telling people cannot be solved.
1 Ton of cooling will eliminate 12,000 BTU/hr of heat.
12,000 BTU/hr will be produced by 3.516 kW of power used by equipment.
1 Ton of cooling will then handle 3.516 kW of equipment load based heat exhaust.
How is high carbon steel used?
High carbon steel remains popular for a wide variety of uses. This type of steel is preferred in the manufacturing of many tools such as drill bits, knives, masonry nails, saws, metal cutting tools, and woodcutting tools. But that's only the common use
What is the difference between fusion welding an resistance welding?
Fusion welding is just any welding process which inhibites the phase trasition from solid to liquid and then back to solid state, while electric resistance welding is based on purely ohmic heating of the different parts, this heat will create fusion of the metal. So; Electric resistance welding can be said to be a type of fusion welding, but not the other way around.
What is the purpose for nozzle?
as a geometrical analysis of the diffuser, the cross sectional area will be increased and converts the pressure into velocity, so the steam pressure will be drops and its velocity will be increased.
What is the practical application of cast iron and steel?
Cast Iron is great for drainage and steel piping is good for venting (galvanized , or wrought iron or yalloy ) for venting
What does a high degree of freedom mean?
A high degree of freedom means that an appendage can pivot or rotate in numerous of ways. The definition of 'high' is not specifically defined, but usually an appendage that can pivot or rotate in more than six or seven ways is considered to have a high degree of freedom.
What are the holding devices for lathe?
A chuck is used to hold small cylindrical jobs in a lathe. Various chuck types like 3-, 4- and 6-Jaw self centering chucks or independent 4-Jaw chucks can be used. Some small cylindrical jobs can also be held between two centers on a lathe.
