M C Q s D r i v e

Mechanical Engineering Mcqs 1919 MCQs [All-Courses]

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Mechanical Engineering MCQs prepared for job test and interview preparation, especially for fresh graduates, students, and candidates appearing in competitive exams. These multiple-choice questions cover key topics such as Machine Design, Theory of Machines, Hydraulic Machines, and other important mechanical engineering concepts.

Emissivity of a white polished body in comparison to a black body is________________?
A higher
B lower
C same
D depends upon the shape of body
Correct Answer: lower
Two balls of same material and finish have their diameters in the ratio of 2 : 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of____________________?
A 1 :1
B 2: 1
C 1 : 2
D 4 : 1
Correct Answer: 1 : 2
Heat conducted througfi unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called__________________?
A thermal resistance
B thermal coefficient
C temperature gradient
D thermal conductivity
Correct Answer: thermal conductivity
A grey body is one whose absorptivity_________________?
A varies with temperature
B varies with wavelength of the incident ray
C is equal to its emissivity
D does not vary with temperature and. wavelength of the incident ray
Correct Answer: is equal to its emissivity
The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as ________________?
A emissivity
B transmissivity
C reflectivity
D intensity of radiation
Correct Answer: intensity of radiation
In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by___________________?
A convection
B radiation
C conduction
D both convection and conduction
Correct Answer: conduction
Unit of thermal diffusivity is_________________?
A m2/hr
B m2/hr°C
C kcal/m2 hr
D kcal/m.hr°C
Correct Answer: m2/hr
Film coefficient is defined as Inside diameter of tube________________?
A Equivalent thickness of film
B Thermal conductivity Equivalent thickness of film Specific heat x Viscocity
C Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity
D Film coefficient x Inside diameter Thermalconductivity
Correct Answer: Equivalent thickness of film
Thermal conductivity of wood depends on_______________?
A moisture
B density
C temperature
D all of the above
Correct Answer: all of the above
Thermal diffusivity is ____________________?
A a dimensionless parameter
B function of temperature
C used as mathematical model
D a physical property of the material
Correct Answer: a physical property of the material