Explore BrainMass

# Mechanical Engineering

### Hydrostatic Relation Empirical Formulas

An empirical formula relating pressure and density for seawater w/ temperature held constant is: p/pa = (k+1)(q/qa)^7 - k where p= pressure pa = pressure at the surface k = dimensionless constant q = density qa = density at the surface Using the formula in the

### Number sentences

Komodo dragons are the largest lizards known to man. A 250-pound dragon can eat enough food to increase it body weight by 1/2. Which number sentence could be used to find w, the weight of a komodo dragon after increasing it body weight by 1/2? If eight people share in eating 3/4 of a quart of ice cream, how much will each per

### Bullet Final Velocity in Water

A bullet is fired into water with an initial velocity of 60m/s. Acceleration = -0.4v^3 m/s^2. Find the velocity of the bullet and the distance it has traveled into the water after 4 seconds. Please show detailed step by step process to solution.

### Mass moment of inertia of a steel part.

Find the mass moment of inertia of a tool steel part. x1 = 126.0mm x2 = 75.0mm See attached file for full problem description.

### Mechanical Vibrations

1) A machine tool having a mass of 1000 kg and a moment of inertia J = 300 kg-m2, is supported on elastic supports with stiffness's and locations shown. i) Find the natural frequencies of the machine tool. ii) What are the corresponding amplitude ratios? (There are 2 separate questions in 1 problem). Please see attached

### Finding Magnification factor M for Frequency Ratio

1) In the idealized model attached shown, m = 15 kg, k = 135 N/m, and the viscous damping ratio is 0.15. Assume that an external harmonic force F(t) = 15 cos 4 t acts on the system with F0=15 N and forcing frequency of 4 rad/s. i) Find the magnification factor M for the frequency ratio r of 1.382. ii) What is the amplitude o

### Matrix equation of motion

1) For the two degree of freedom structure shown: i) what is the matrix equation of motion?. Assume that m1 and m2 oscillate harmonically with the same frequency but with different amplitudes X1 and X2 of x1(t) and x2(t). ii) what are the values of the amplitude ratios r1 and r2 if m1 = m2 = m, k1 = k, and k2 =3k? See a

### Equation of Motion by Lagrange Method

Advanced dynamics. See attached file for full problem description.

### Advanced dynamics and mechanical vibration

Advanced dynamics. See attached file for full problem description.

### Maintaining a Large Refrigeration Plant

A large refrigeration plant is to be maintained at -15C, and it requires refrigeration at a rate of 100kW. The condenser of the plant is to be cooled by liquid water, which experiences a temperature rise of 8C as it flows over the coils of the condenser. Assuming the plant operates on the ideal vapor-compression cycle using refr

### The compression ratio of an air-standard Otto cycle is 9.5

The compression ratio of an air-standard Otto cycle is 9.5. Prior to the isentropic compression process, the air is at 100 kPa, 17 C, and 600 cm2. The temperature at the end of the isentropic expansion process is 800K. Using specific heat value at room temperature, determine: 1. The highest temperature and pressure in the

### Flow Rate - Manometer

Water flows through the pipe contraction shown in the figure below. For the given 0.2 m difference in the manometer level, determine the flowrate as a function of the diameter of the small pipe, D. See attached file for full problem description.

### An ideal vapor-compression refrigeration cycle uses R-134a

An ideal vapor-compression refrigeration cycle uses R-134a as the working fluid in an air-conditioning system. The refrigerant enters the compressor as a saturated vapor at 40 °F and leaves the condenser as a saturated liquid at 130 °F. The mass flow rate of the refrigerant is 1.5 lbm/s. Calculate the following: a. The hea

### Moment of Force Problem

1. Three forces F1, F2, and F3 or magnitude 40 N, 100N and 20 N are acting on a point. The direction of the forces are 0,-30 and +120 degrees from the positive X axis. Determine the magnitude and direction of the resultant force.

### Dynamics Projectile Problem

A hunter in the plains of Africa is equipped with a bow and arrow. The maximum range of the bow is 100 m. If a Lion charges straight towards him at 30 km/h and the hunter aims his bow at 20 degrees relative to the horizontal, find: (a) time of flight of the arrow (b) arrow velocity (c) how far away should the lion be when t

### A Tricky String Pulley Problem in Dynamics

Problem # 2 - If the end of the cable at A is pulled down with a speed of 2 m/s, determine the speed at Which block B rises. Give logical explanation i.e. qualitative as well as quantitative way. For figure, please see attached file.

Collar C slides relative to the curved rod at a constant speed u, while the rod rotates about the horizontal axis at the constant rate. Determine the acceleration of the collar in terms of theta.

### A turbine salesman makes the following claim

A turbine salesman makes the following claim for one of his products: Steam enters a steady-flow adiabatic turbine at 4 MPa, 600 °C with negligible velocity and exhausts at 200 kPa with a velocity of 180 m/s. The flow rate is 2.2 kg/s and the turbine power is 2 MW. a. If the turbine operated as described by the salesman, w

Refrigerant R-134a is compressed steadily and adiabatically in a reversible compressor. The volume flow rate entering the compressor is 800 ft3/min. The R-134a enters the compressor at 120 psia, 100 °F and leaves with its pressure being twice the inlet value. Neglect kinetic energy changes, and calculate the power required t

### Employing the Ideal Gas Model, Determine the Change

Employing the ideal gas model, determine the change in specific entropy between the indicated states, in Btu/lbmol?ºR. Solve 2 ways: Use the appropriate ideal gas table AND also by using a constant specific heat value. a) Air, P1 = 1 atm, T1 = 40 ºF, P2 = 1 atm, T2 = 400 ºF b) Air, P1 = 20 psia, T1= 100 ºF, P2 = 60 psia,

### Refrigeration cycles

A refrigeration system using refrigerant 22 is to have a refrigerating capacity of 80 kW. The cycle is a standard vapor-compression cycle in which the evaporating temperature is -8 degrees Celsius and the condensing temperature 42 degrees Celsius. (a) Determine the volume flow of refrigerant measured in cubic meters per seco

### A heat pump is used to maintain a house

A heat pump is used to maintain a house at a constant temperature of 23 °C. The house is losing heat to the outside air through the walls and the windows at a rate of 60,000 kJ/hr while the energy generated within the house from people, lights, and appliances amounts to 4000 kJ/h. For a Coefficient of Performance (COP) of 2.5,

### Refrigerant 134a enters a heat exchanger in a steady state refrigeration system as saturated

Refrigerant 134a enters a heat exchanger in a steady state refrigeration system as saturated vapor at 0 °F and exits at 20 °F with no change in pressure. A separate liquid stream of Refrigerant 134a passes in counterflow to the vapor stream, entering at 105 °F, 160 psia and exiting at a lower temperature while experiencing n

### Surface area and volume of object

Calculate the volume and total surface area of a shape that has been rotated through 180 degrees. Please see the attached file.

### Energy Analysis Of Closed Piston Systems

A mass of 15 kg of air in a piston-cylinder device is heated from 25 to 77 degrees Celsius by passing current through a resistance heater inside the cylinder. The pressure inside the cylinder is held constant at 300 kPa during the process, and a heat loss of 1.0 kJ occurs. Determine the electric energy supplied, in kWh. Answ

### Energy Analysis Of Closed Systems

A 4 x 5 x 7 m room is heated by the radiator of a steam heating system. The steam radiator transfer heat at a rate of .... Please show all work step by step and include all applicable formulas. (See attached file for full problem description)

### Energy Analysis or a Closed System Piston

Hydrogen is contained in a piston-cylinder device at 14.7 psia and 15 ft3. At this state , a linear spring (F x) witha spring constant of 15,000 lbf/ft is touching the piston but exerts no force on it. The cross-sectional area of the piston is 3 ft2. Heat is transferred to the hydrogen, causing it to expand until its volume dou

### Determining the exit velocity from an air nozzle

Air enters a nozzle operating at steady state at 800 ºR with a negligible velocity and exits the nozzle at 570 ºR. Heat transfer occurs from the air to the surroundings at a rate of 10 Btu per pound of air flowing. Assuming ideal gas behavior and neglecting potential energy effects, determine the velocity at the exit in ft/s.

### Steam Enters a Turbine Operating at Steady-State

Steam enters a turbine operating at steady-state at 700 ºF and 600 lbf/in2 and leaves at 0.6 lbf/in2 with a quality of 90%. The turbine develops 12,000 hp, and heat transfer from the turbine to the surroundings occurs at a rate of 2.5x106 Btu/h. Neglecting kinetic and potential energy changes from inlet to exit, determine the

### Refrigerant R-134a vapor in a piston-cylinder assembly

Refrigerant R-134a vapor in a piston-cylinder assembly undergoes a constant-pressure process from saturated vapor at 800 kPa to 50 ºC. For the refrigerant, determine the work and the heat transfer, per unit mass (each in kJ/kg). Changes in kinetic and potential energy are negligible.