Question: Choose the wrong statement ?

• 1. any weight, floating or immersed in a liquid, is acted upon by a buoyant force
• 2. Buoyant force is equal to the weight of the liquid displaced
• 3. The point through which buoyant force acts, is called the center of buoyancy
• 4. Center of buoyancy is located above the center of gravity of the displaced liquid v

Question: Choose the wrong statement?

• 1. The horizontal component of the hydro-static force on any surface is equal to the normal force on the vertical projection of the surface
• 2. The horizontal component acts through the center of pressure for the vertical projection
• 3. The vertical component of the hydrostatic force on any surface is equal to the weight of the volume of the liquid above the area
• 4. he vertical component passes through the center of pressure of the volume

Question: Total emissivity of polished silver compared to black body is___________________?

• 1. same
• 2. higher
• 3. more or less same
• 4. very much lower

Question: The value of Prandtl number for air is about _______________________?

• 1. 0.1
• 2. 0.3
• 3. 0.7
• 4. 1.7

Question: The energy distribution of an ideal reflector at higher temperatures is largely in the range of ___________________?

• 1. shorter wavelength
• 2. longer wavelength
• 3. remains same at all wavelengths
• 4. wavelength has nothing to do with it

Question: Which of the following property of air does not increase with rise in temperature ________________?

• 1. thermal conductivity
• 2. thermal diffusivity
• 3. density
• 4. dynamic viscosity

Question: In free con-vection heat transfer, Nusselt number is function of________________?

• 1. Grashoff no. and Reynold no
• 2. Grashoff no and Prandtl no.
• 3. Prandtl no. and Reynold no
• 4. Grashoff no., Prandtl no and Reynold no

Question: According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to___________________?

• 1. absolute temperature
• 2. square of temperature
• 3. fourth power of absolute temperature
• 4. fourth power of temperature

Question: Log mean temperature difference in case of counter flow compared to parallel flow will be________________?

• 1. same
• 2. more
• 3. less
• 4. depends on other factors

Question: The unit of Stefan Boltzmann constant is ____________________?

• 1. watt/cm2 °K
• 2. watt/cm4 °K
• 3. watt2/cm °K4
• 4. watt/cm2 °K4