# Mechanical Engineering

## A plane wall with surface temperature 350C is attached with straight rectangular fins( k =235 W/m K). The fins are exposed to an ambient air condition of 25C and the convection heat transfer coefficient is 154 W/m2. Each fin has a length of 50mm, a base of 5 mm thick and a width of 100mm. For a Single fin, using a uniform nodal spacing of 10 mm, determine (a) the finite difference equations, (b) the nodal temperatures by solving the finite difference equations, and (c) the heat transfer rate and compare the result with analytical solution.

A plane wall with surface temperature 350C is attached with straight rectangular fins( k =235 W/m K). The fins are exposed to an ambient air condition of 25C and the convection heat transfer coefficient is 154 W/m2. Each fin has a length of 50mm, a base of 5 mm thick and a width of 100mm. …

## Select the lightest column section for column AB in the frame shown. The column is under an ultimate load of 700k and only in-plane behavior is considered. Furthermore, assume that the column immediately above or below AB are the same size as AB. All beams are of W18x40 sections. Fy =50ksi . Assume: Inelastic Behavior. Assume any appropriate assumption

EXPERT ANSWER 1. Here it is given thatUse W14×61Fy = 50ksiNow, design strength of column AB Pu = 2658.45kDesign Strength of column AB = 2658.45k2. Let us first design column AB and then Base plate design must be doneAssuming both ends fixed. The effective length is 0.65×16 10.4 feet.Using LRFD, the factored load is Pu=1.2×350+1.6×450=1,140kips  …

## A. Differentiate Coulomb’s and Rankine’s Theories B. Collect the data of at least 5 retaining walls constructed in Pakistan. The details should include the following information. 1. Type and purpose of the wall 2. Technical specification 3. Materials used 4. Current status (Stable/maintained/upgraded) 5. location with photographic evidence 6. your suggestions for improvement or comments on the flaws if exist.

EXPERT ANSWER A.Rankine’s Earth Pressure Theory. The Rankine’s theory assumes that there is no wall friction (δ=0) , the ground and failure surfaces are straight planes, and that the resultant force acts parallel to the backfill slope. Rankine’s Theory At Rest Earth Pressure: The at-rest earth pressure coefficient (Ko) is applicable for determining the active …

## The Hoover Dam, in Arizona, encloses Lake Mead, which contains 10 trillion gallons of water. The dam is 1200 ft wide and the lake is 500 ft deep. ( a ) Estimate the hydrostatic force on the dam, in MN. ( b ) Explain how you might analyze the stress in the dam due to this hydrostatic force.

The Hoover Dam, in Arizona, encloses Lake Mead,which contains 10 trillion gallons of water. The dam is1200 ft wide and the lake is 500 ft deep. ( a ) Estimate thehydrostatic force on the dam, in MN. ( b ) Explain howyou might analyze the stress in the dam due to this hydrostaticforce. EXPERT ANSWER