Explore BrainMass

Mechanical Engineering


a) What is the resistance of the wire? (see attachment for diagram and full questions) b) If a voltage of 1mV=10^-3volts is applied across the wire, what is the current (I) and current density (J) along the wire? c) Taking 1 electron per atom as conducting (we will justify later, why most of the Cu e-`s do not contribute),

In an air conditioning system for a precision gauge laboratory

In the attached problem, there is a solution to part a attached. Please solve part b completely. In an air conditioning system for a precision gauge laboratory, atmospheric air at 32 C, 101.3 kPa and 80% relative humidity is first chilled to 10 C to remove moisture...

Rotation bars and slider

Rod AB is rotating 4rad/s clockwise. The speed in m/s of the slider is what in m/s? (See attached file for full problem description)

Motor and power cuts

A motor is running at 12 rpm and the switch is flipped and cuts the power. The rotor weighs 75 lbs. The radius of gyration of the rotor is 6``. The rotor experiences an average friction moment 6 lb/in. How many seconds does it take for the rotor to come to rest?

Compressive stress

A circular cross sectional bar with a diameter of 3.25 inches is loaded with a uniform axial compressive load of 22,750 pounds. What is the compressive stress along a cross section of the bar? A. Cannot be determined because the length of the bar is unknown B. Over 10,000 psi C. Less than 1,000 psi D. Between 2,000 and 9

Workout velocity and range of shell fired

1. Why is it possible to consider the vertical and horizontal motion of a projectile independently of each other. 2. A mortar shell fired with an angle of elevation of 50 degrees ahs a range of 2.5 km. Neglecting air resistance determine: a. The time of flight. b. The shells initial velocity. c. The shells range and heig

Tensile force formulas

A cylindrical steel beam is 2 inches diameter and 6 feet long. The modulus of elasticity is 30 x 1,000,000 psi. If the beam is subjected to a tensile force of 1000 lbs, what will be the resulting unit strain? A. 16,000 psi B. .002 ft-lbs/sq-in C. 0.000064 ft/ft D. .0000106 in/in

Relative Acceleration of two cars

Two cars split onto seperate roads. One goes straight and the other peels ot the right. What is the acceleration of B with respect to A in mi/hr^2 at the point shown in the figure? --- (See attached file for full problem description)

Pulleys with an Acceleration Component

A pulley system is released from rest. Find the acceleration of both of the weights on the pulleys. --- (See attached file for full problem description)

Maximizing a function

What value of x will maximize: r(x)=r^2*(ln(1/x)? x can take values between 1/4 and 1

Hazen-Williams Formula : Find the Diameter of a Pipe

The length of cast-iron pipe is to be 4200 ft., and the head causing flow is to be 12.6ft. After the pipe has been in service 5 years, it is expected to discharge water at a rate equal to 3.2 cfs. Using a Hazen-Williams Formula Chart in which C = 160 What is the diameter of the pipe? 16 in., 12 in., 14 in., 10 in. The head fl

Angular acceleration/velocity of a bar

Bar ABCD is guided by two blocks at B and C moving in slots as shown. Block B moves downward at a constant speed of Vb = 10ft/s. Using the method of instantaneous center of zero velocity, determine (a) the angular velocity of the link, (b) the velocity of the block C at the instant when theta = 35 degrees, and (c) the angular ac

Heat pump for house

Ever wonder if you can build a machine to heat up your house using the heat from the outside environment? Well you'll need to start with the heat pump concept. In this example, you'll learn how to determine the maximum theoretical coefficient of performance for a heat pump operating at steady state between a dwelling at 70 de

Specific and Relative Humidity

You have a box that contains 100 kmoles of dry air and 1 kmole of water vapor. The contents are at a pressure of 100 kPa. Someone says that they need to have the enthalpy of the mixture to be 63.8 kJ/kg dry air where 0 degrees Celsius is the reference temperature at which enthalpy is zero. Find the following: a.) The Specif

Water is the working fluid in an ideal Rankine cycle.

Water is the working fluid in an ideal Rankine cycle. Saturated vapor enters the turbine at 18 MPa. The condenser pressure is 6 kPa. How do I determine the quality of the fluid at the turbine exit, and the heat transfer to the steam passing through the boiler in kJ per kg of steam flowing. The enthalpy of the steam entering the

Determining Feasibility

At steady state, a new power cycle is claimed by its inventor to develop 6 horsepower for a heat addition rate of 400 Btu/min. If the cycle operates between reservoirs at 2400 and 1000 deg R, is the claim feasible?

Determine the Mass of Ammonia

Ammonia is stored in a tank with a volume of 0.21 m^3. How do I determine the mass, in kg, assuming saturated liquid at 20 deg C.

Find the Temperature of the Refrigerant

A closed vessel with a volume of 2 ft^3 contains 5 lb of Refrigerant 134a. A pressure sensor in the tank wall reads 71.39 lbf/in.^2 (gage). If the atmospheric pressure is 14.4 lbf/in.^2 how do I find the temperature of the refrigerant, in deg F?

Determine the Final Velocity

An object whose mass is 1 lb has a velocity of 100 ft/s. How would I determine the final velocity, in ft/s, if the kinetic energy of the object decreases by 100 ft*lbf? What would be the change in elevation, in ft. associated with the 100 ft*lbf change in potential energy if g=32.0 ft/s^2?

Turbine Thermal Efficiency

Steam @ 10 MPa, 600 degrees celcius enters the first-stage turbine of an ideal Rankine cycle with reheat. The steam leaving the reheat section of the steam generator is @ 500 degrees celcius, and the condensor pressure is 5 kPa. If the quality at the exit of the second-stage turbine is 90%, determine the cycle thermal efficien

Amplitude of Motion; System Response Equation

1. The spring - mass system shown in figure 1 (see attached) is subjected to a triangular force for the time duration td. Determine... (a) the amplitude of the motion at time ... (b) the system response equation after time .... Please see attachment for complete question. Thanks

Mechanics of Materials

Question: Two full-size 2x6 inch planks are connected as shown by lag screws to form a beam which is subject to a vertical shear of 400 lb. Knowing that the allowable shearing force is 360 lb in each lag screw, how would I determine the largest permissible longitudinal spacing (s) of the lag screws, and the maximum shearing stre

Mechanics of materials1678

The rigid bar ABCD is suspended from three identical wires as shown. Knowing that a=b, how would I determine the tension in wires A, B, and D caused by the load P applied at C?

Mechanics of materials1213

For the beam and loading shown how do I find the maximum absolute values for the shear and bending moment?

Mechanics: Bending Moment

Question: Semicircular grooves of radius r must be milled in the top and bottom portions of a steel bar as shown in the attached file. Using an allowable stress of 100 MPa, how do I determine the largest bending moment which may be applied to the bar shown when the radius of the semicircular grooves is 20 mm?