ISRO Scientist or Engineer Mechanical 2014
For the following questions answer them individually
A vertical air stream flowing at a velocity of 100 m/s supports a ball of 60 mm in diameter. Taking the density of air as 1.2 kg/m$$^3$$ and kinematic viscosity as 1.6 stokes, the weight of the ball that is supported is (if coefficient of drag $$C_D = 0.8$$)
The velocity distribution for flow overa flat plate is given by $$U = \left(\frac{3}{4}\right)y - y^2$$ in which u is the velocity in m/s at a distance y meter above the plate. If the dynamic viscosity of the fluid is 10 poise, then the shear stress at 0.2 m is
Determine $$M_{eq}$$ and $$K_{eg}$$ for the system in below Fig., when X, the downward displacement of the block, measured from the system's equilibrium position, is used as the generalized coordinate. Take I as the M.I. of the wheel.
The system described by the following governing equation of motion, will have how many natural frequencies?
$$\begin{bmatrix}m & 0 \\0 & m \end{bmatrix}\begin{bmatrix}\ddot{x1} \\\ddot{x2} \end{bmatrix} + \begin{bmatrix}2k & -k \\-k & 3k \end{bmatrix}\begin{bmatrix}x1 \\x2 \end{bmatrix} = \begin{bmatrix}0 \\0 \end{bmatrix}$$
Find out the correct free body diagram for the middle mass for the given spring- mass system in below figure.
For what value of m (mass) will resonance occur for the spring-mass system given below with the given spring constants?
Surface A in the figure is coated with white paint and maintained at temperature of $$27^\circ C$$. It is located directly opposite to surface B which can be considered a black body and maintained at temperature of $$727^\circ C$$. Calculate the amount of heat that needs to be removed from surface A per unit area to maintain its constant temperature. (consider emissivity of the white paint = 1 and view factor = 1, $$\sigma$$ = Stefan — Boltzmann constant)
The convective heat transfer coefficient h is defined by the relationship (m=mass, Cp=specific heat, k= conductivity, q = heat flow rate, Nu = Nusselt Number, L = Thickness, $$\triangle T$$ = Temperature difference)
The figure below shows a cross section through an insulated heating pipe which is made from steel (k=45 W/m K) with an inner radius of 150mm and outer radius of 155 mm. The pipe is coated with 100 mm thickness of insulation having thermal conductivity of k = 0.06 W/m K. Air at inlet temperature $$Ti = 60^\circ C$$ flow through the pipe has a value of convective coefficient hi = 35 W/m$$^2$$ K. The outside surface of the pipe is surrounded by air which is at $$15^\circ C$$ and convective heat transfer coefficient on this surface has a value of ho = 10 W/m$$^2$$ K. Find the critical insulation radius?
