Latest Updates in Mechanical Engineering

• 1 HP=how much rpm

We need Torque to find out.

Apply this formula:

T = HP x 5252
           rpm

T = torque (in lb-ft)
HP = horsepower
5252 = constant
rpm = revolutions per minute

• Which mechanism is used in automobile gearing system

Differential mechanism

• Why different types of sound are produced in different bikes though they say run on SI engine

Engine specifications are different in different manufactures like as bore diameter(cc), ignition timing. Also the exhaust passage take more responsible for sound.

• Why entropy decreases with the increase in temperature?

ds=dQ/T

Entropy is inversely proportional to the temperature so.as temp. increases,entropy decreases

• What type of metal is used in a propeller

Aluminium,stainless steel,magnesium bronze, NIBRAL (nickel,brass,aluminium)

• Why involute curve used in gear

1) it’s smooth to drive the gear.
2) in gears contact is only point, this type is curve take the more load than normal one

• 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.

• In condensation of steam power plant, steam sent in shell side and cooling water on the tube side because

  1. To increase overall heat transfer coefficient of water side velocity can be increases if water is on the tube side
  2. Condenser can act as a storage unit for condensed steam
  3. Rate of condensation of steam is invariably smaller than the mass flow rate of cooling water
  4. It is easier to maintain vacuum on the shell side than on the tube side

Answer:

1. To increase overall heat transfer coefficient of water side velocity can be increases if water is on the tube side

Reason:

Specific volume of steam is larger so more volume is required in condenser

• Why freezer in the fridge is placed in top level?

Because density of cold air is higher than warm air,hence it is placed at top.Cold air comes downward & cool the bottom part.

• What is more dangerous longitudinal stress or Hoop stress and why?

Hoop stress is more dangerous than longitudinal stress, because the dangerous area coming under the hoop stress is circumferential,while in longitudinal,the axial area will come under dangerous area will will be less than circumferential area.So the hoop stress is more dangerous than longitudinal stress

• In a spray washing system, if the water temperature is higher than the dry bulb temperature of entering air then the air is

  1. Heated and dehumidified
  2. Heated and humidified
  3. Cooled and humidified
  4. Cooled and dehumidified

Answer:

Heated and humidified