March 2017

Reinforced Concrete

Submitted by marshmallow on March 1, 2017 - 9:32pm

– A reinforced concrete girder is subjected to torsional moment from the loads on the cantilever
frame. The following factored forces are computed from
this beam:

Factored moment, Mu = 290kN-m
Factored shear, Vu = 220 kN
Factored torque, Tu = 180 kN-m

Viviano James Gonzales G's picture

Dynamics (need this badly this day)

Submitted by Viviano James G... on March 2, 2017 - 12:50am

The weather vane of a ship points southeast when the ship is moving east at the rate of 25 km/hr. If the wind velocity is 5 km/hr., from what direction is it blowing?

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Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:51am

A 400N weight starts down a 300 incline with an initial velocity of 4m/s. What is the velocity of the weight after 10 seconds if F=0.20 for the incline?

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Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:51am

What work is done on a level track in bringing the velocity of a train weighing 200metric tons from zero to 45 kph, if the frictional resistance at any velocity is 45N/ton, and if the change in speed is accomplished in length of 1000m? (Ans. 26780.95 KN/m)

C. If the track were a 1% upgrade, what would be the additional work to be done?

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Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:52am

28. A train, weighing 9000KN, is pulled up a 2% grade. Train resistance is constant at 6N/KN. The speed of the train is increased 8m/s to 16m/s in a distance of 800m. Find the maximum horsepower developed by the locomotive.

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Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:53am

turbine is rotating at a constant speed of 2,400rev/min. at what constant rate, in radians/s2, must its motion be retarted to bring it to rest;

a. In 20 mins.
b. In 300 revolutions

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Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:54am

what superelevation is required on a 40 railway curve for zero resultant flange pressure on a car running at a speed of 64kph?

C. What is the resultant flange pressure on a 450KN car moving around this curve at a speed of 96KPH.
Gage G of the track is 1.50m. (A 40 curve is one whose chord is 30.5m)

Viviano James Gonzales G's picture

Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:54am

17. At what speed must a 1000kg car approach a ramp which has a slope and 12m high at the top such that it will just coast to the top. Assume the constant retarding force due to friction, wind, etc. to be 60kg.

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Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:55am

13. The straight post B rests upon the front edge of the car A as shown which is ascending the 300 incline with an acceleration of 0.5 m/s2.at what angle must the post be inclined in order that it will maintain its position?

Viviano James Gonzales G's picture

Need this badly today

Submitted by Viviano James G... on March 2, 2017 - 12:56am

The weather vane of a ship points southeast when the ship is moving east at the rate of 25 km/hr. If the wind velocity is 5 km/hr., from what direction is it blowing?

Mhar Jhune's picture

Application of Differential Equation: Newton's Law of Cooling

Submitted by Mhar Jhune on March 3, 2017 - 2:33pm

At 2:00PM, a thermometer reading 80°F is taken outside where the air is 20°F. At 2:03PM, the temperature reading yielded by thermometer is 42°F, later the thermometer was brought inside where the air is at 80°F, at 2:10PM the reading is 71°F. When was the thermometer brought indoor?

Problem 907 | Combined Axial and Bending

Problem 907
Determine the largest load P that can be supported by the circular steel bracket shown in Figure P-907 if the normal stress on section A-B is limited to 80 MPa.
 

907-circular-bracket.gif

 

Problem 908 | Combined Axial and Bending

 Problem 908
A punch press has the cast steel frame shown in Figure P-908. Determine the greatest force P that can be exerted at the jaws of the punch without exceeding a stress of 18 ksi at section A-B. The properties of the area are as shown and 1-1 is the centroidal axis.
 

908-punch-press.gif

 

Problem 01 | Stress in Helical Spring

Situation
The helical spring shown is axially loaded with a compression force P equal to 5 kN. The mean diameter of the spring is 100 mm and the wire used is 10 mm as indicated in the figure.

  1. What is the shear stress at A?
  2. What is the shear stress at B?
  3. On diameter AB, locate the point of zero stress measured from C.

 

001-spring-torque-plus-shear.png

 

Fluid Mechanics and Hydraulics

Absolute Pressure, Gage Pressure, and Atmospheric Pressure

$p_{abs} = p_{gage} + p_{atm}$

 

Variations in Pressure

$p_2 = p_1 + \gamma h

 

Pressure Head

$h = \dfrac{p}{\gamma}$

 

Centroid of Composite Area: Rectangle and Two Triangles

Submitted by Dolpson on March 12, 2017 - 3:53pm

I want the solution to this question img_20170307_084352.jpgplease

Principles of Hydrostatic Pressures

Unit Pressure
Unit pressure or simply called pressure is the amount of force exerted by a fluid distributed uniformly over a unit area.
 

$p = \dfrac{Force, \, F}{Area, \, A}$

 

If the unit pressure is not uniform over the unit area, it can be expressed as the sum of differential pressure.
 

$\displaystyle p = \int \dfrac{dF}{dA}$

 

001-blaise-pascal.jpg
Blaise Pascal (1623 – 1662)

 

Since fluid at rest cannot resist shearing stress, pressure is always at right angle to the area where it is acting. It is also worthy to note that the total hydrostatic force F = pA, which can be found by cross multiplication.
 

Variation of Pressure with Depth in a Fluid

Consider two points 1 and 2 lie in the ends of fluid prism having a cross-sectional area dA and length L. The difference in elevation between these two points is h as shown in Figure 02 below. The fluid is at rest and its surface is free. The prism is therefore in equilibrium and all forces acting on it sums up to zero.
 

000-variations-in-pressure.gif

 

Note: FFS stands for Free Fluid Surface which refers to fluid surface subject to zero gauge pressure.
 

Problem 01 - Variation of Pressure

Problem
Determine the pressure in a vessel of mercury, specific gravity 13.6, at a point 20 cm below the surface. Express the answer in N/m2.
 

Problem 02 - Variation of Pressure

Problem
Determine the pressure on the face of a dam at a point 12 m below the water surface, in (a) kilo Pascal gauge; (b) kilogram per square meter gauge; (c) kilo Pascal absolute; (d) pounds per square foot gauge; (e) pounds per square inch gauge; and (e) pounds per square inch absolute.
 

Problem 03 - Variation of Pressure

Problem
Take sea water to be 3% heavier than fresh water and assume it is incompressible. What is the pressure, in metric ton per square meter, at 3.22 km below the surface of the ocean if fresh water weighs 9.79 kN/m3?
 

Problem 04 - Variation of Pressure

Problem
What height of mercury column will cause a pressure of 680 kPa? What is the equivalent height of water column?
 

Problem 05 - Variation of Pressure

Problem
At what depth in a stand pipe containing water is the pressure 200 kPa?
 

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