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# Mechanical Engineering

### Dynamics Problem - Backspin (Friction, Velocity)

A 1.2ft diameter ball is thrown onto a rough surface, such that it has a velocity of 6ft/s and a backspin angular velocity of w. If it is to stop backspinning at the same instant as the velocity is 0, the backspin w in rad/s is what? HINT: The answer is independent of the mass and coefficient of friction. a. 17.8 b. 22.0 c. 2

### Dynamics Problem - Tangential Acceleration an Velocity

A board rides on two driving drums. At the instant shown (*see attached), the board has the acceleration noted. If the board is not slipping on the drums and the total acceleration of the drum contact points is 3m/s[squared], the velocity in m/s of the board at this instant is closest to which answer choice? a. 0.8 b. 0.9 c

### Calculating maximum velocity, displacement and stretch

The pair of blocks, which are connected by a cord, are released from rest when the spring is unstretched. The static and kinetic coefficients of friction are .2 and .1, respectively. The following things are to be found using the work-energy methods: 1) Maximum Velocity of the blocks 2) Stretch of the spring at the maximu

### Thermodynamics Problem: Heat Pump

Hi, I am confused about how to answer the following question. Any assistance would be appreciated. Question: A heat pump with a COP (coefficient of performance) of 2.8 is used to heat an air-tight house. When running, the heat pump consumes 5 kW of power. If the temperature in the house is 7 degrees Celsius when the heat pum

### Combustion Reactions: Thermochemistry

1. The analysis by mass of a sample of petrol was 85.5% C and 14.5% H2. Calculate the stoichiometric A/F ratio. Also determine the actual A/F ratios and the dry analyses for mixture strengths of 90% and 120%. 2. Find the stoichiometric A/F ratio (by mass) for the combustion of benzene (C6H6). Compute the actual A/F ratio and do

### Combustion Reactions and Thermochemistry

Liquid Octane at 25C, 1 bar is burned with air at 500K in a steady flow combustor. The products of combustion are cooled to 1400K, 1 bar and have the following volumetric analysis on a dry basis: 10.7% CO_@; 3.6% CO; 5.3% O_2 and 80.4% N_2. Determine the percentage excess air supplied, the dewpoint of the products and the heat t

### Angular Impulse Force

Assuming an angular impulse =0.5*3(25/12)=3.125pound*ft*sec and an impact that takes 0.1 second, with what force (in pounds force) will the door strike the door jamb? Please provide an explanation with the equations, arithmetic calculations and units.

### Strain, Force and Distance

A particular grade of Nitinol SMA is capable of upto 6% strain recovery and develops an internal restoration stress of upto 300 MN m-2. Estimate the amount of force and distance of travel that could be triggered by warming a rod(20mm long,1mm diameter) of this material that had been permanently stretched(6%strain) when cold.

### Polymer identification & protein adsorption

I need to understand the relationship between polymer charge ( +, -, neutral) and protien adsorption

### Design Engineering (Determine Shift Diameter)

A mild steel shaft is required to transmit 3 kw at 2.33 r/s. Determine the shift diameter assuming a maximum all sheer stress of 65 MPa.

### Design Engineering: Find Load and Heat Generated Per Minute

A load of 6400 Kg is carried by a journal rotating in a 270 mm bearing diameter and 400 mm long. Find the specific load on the bearing and the heat generated per minute in the bearing, assuming the shaft speed is 4 r/s and the coefficient of friction is 0.018.

### Design Engineering (Working Stress; Length:Diameter Ratio)

2) Find the diameter and length of a mild steel end journal on which there is a load of 35 KN (shock loading). Assume a safe working stress of 40 MPa and a lengh:diameter ratio of 1.5

### Pressure Cooker and Mass Flow Rate

Steam is leaving a pressure cooker whose operating pressure is 30 psi. It is observed that the amount of liquid in the cooker has decreased by 0.4 gal in 45 minutes after the steady operating conditions are established, and the cross-sectional area of the exit opening is 0.15 in^2. Determine (a) the mass flow rate of the steam a

### Calculating a Constant Pressure Process

In a constant pressure, nonflow process, 6Btus of heat are added to a gas while the volumes change from 1.6ft^3 to 2.0ft^3. If the temperature decreases by 10*F and the system contains 2 lbm of gas, find the pressure in the system. (Cv=.2Btu/lbm*F) 1Btu=778 ft-lbm

### Rate of Evaporation

Water is to be boiled at sea level in a 30-cm-diameter stainless steel pan placed on top of a 3-kW electric burner. If 60% of the heat generated by the burner is transferred to the water during boiling, determine the rate of evaporation of water. See Figure 2-39 attached. Please show steps.Thanks.

### Superheated Water Vapour

Superheated water vapour at 180 psia and 500 degrees Farenheit is allowed to cool at a constant volume until the temperature drops to 250 degrees Farenheit. At the final state, determine: (a) the pressure (b) the quality (c) the enthalpy. Also, show the process on a T-v diagram with respect to saturation lines.

### Boundary Layer Theory and Turbulent Flow in Pipes.

a) Calculate the power required to overcome the skin friction drag on the keel of a sailing dingy moving through water at 2m/s. The keel projects 0.8m into the water and it is 0.4m wide. Assume that the keel is a smooth flat rectangular plate and that transition from laminar to turbulent flow occurs instantaneously at Re = 4*10^

### Graphs for Static Force Systems

1) An object of weight 20kn is supported from above by two cables, inclined at 40 degrees and 70 degrees to the horizontal. Find graphically the tensions in the cables. 2) Find graphically the forces f1 and f2 in the crane. The triangle is standing up with a 90 degree angle next to the wall on top, with f1 pointing towards

### Cylindrical Pressure for Frictionless Piston Device

A gas is contained in a vertical, frictionless piston cylinder device. The piston has a mass of 4 kg and cross-sectional area of 35 cm^2. A compressed spring above the piston exerts a force of 60 N on the piston (as seen in Figure P1-73 attached). If the atmospheric pressure is 95 kPa. determine the pressure inside the cylinder.

### Thermodynamic Equilibrium

For a system to be in thermodynamic equilibrium, do the temperature and the pressure have to be the same everywhere? Explain.

### Assignment Question 3 in Applied Mechanics

Fig. Q3 shows a rigid light beam which is hinged at O to a wall. The beam carries a point mass of m at the free end. The beam is connected at its mid-point to a spring (stiffness k) which is also connected to a support that moves with a vertical motion y = Y sinwt. A damper (coefficient c) connects the mid-point of the beam to a

### Static force systems

1.An object of weight 20kn is supported from above by two cables inclined at 40 degrees and 70 degrees to the horizontal. Find graphically the tensions in the cables. 2. Find graphically the forces f1 and f2 in the jib crane. the first angle of the triangle are 60degrees, It is at that angle the 2kn force is pulling down on. fo

### Tank flow rate

With the valve closed, water flows from tank A to tank B as shown in the attachment. What is the flow rate into tank B, when the valve is opened to allow water to flow into tank C also? Neglect all minor losses and assume that the friction factor is 0.02 for all pipes.

### Method of Sections Reactions

A. Find the reactions at A & G b. Use the METHOD OF SECTIONS to find the forces in members IJ, EJ, and DE. Indicate also whether in tension or compression. Please see the attachment.

### Bernoulli's Equation Question

A venturi has a large section diameter of 4', where the velocity V1=20ft/sec. The pressure difference between this section and throat, (P1-P2) = 25 psi. If the fluid is sea water (Sg=1.03) what is the diameter of the throat? Use figure #3 attached.

### Cam Curve Design

Design a three-dwell cam to move a follower from 0 to 2.5" in 40deg, dwell for 100deg, fall 1.5" in 90deg, dwell for 20deg, fall 1" in 30deg, and dwell for the remainder. The total cycle must take 10sec. Plot the s,v,a,j diagrams. The polynomial method is to be used to solve the equation. For the graphs, Mathcad or similar progr

### Finding Vertical Distance in Pipe Line System

For the system in attachment, calculate the vertical distance between the surfaces of the two reservoirs when water at 10 degrees celcius flows from A to B at the rate of 0.03 m^3/s. Both pipes are cast iron and the elbows are standard. The total length of the 3" pipe is 100 meters. For the 6" pipe, it is 300 meters.

### Automobile Pump Power

Gasoline is pumped from the gas tank of an automobile to the carburetor through a 10 ft long, 1/4" diameter fuel line of steel tubing. The line has five 90 degree smooth bends with r/d of 6. The gasoline discharges through a 1/32" diameter jet in the carburetor to a pressure of 14 psia. The pressure in the tank is 14.7 psia.

### Forces of Equilibrium - Drawbridge

The drawbridge BCD weighs 1000 lbs. Calculate: (a) the tension in the cable AC. (b) Dx and Dy and the resultant, D. (Please see attachment.)

### Forces of Equilibrium

(Please see the attachment.) 1. (a) Draw a free-body diagram of the system. (b) Find the forces acting on joints A,B & C. (c) Find the resultant A and its direction. Ax = _________ Ay = _________ A = __________ Bx = ___________ By = ___________ Cx = ___________ Cy = ___________