July 2015

Joshua Ocate's picture

derivation: formula for spherical cap

Submitted by Joshua Ocate on July 3, 2015 - 9:34pm

how can I derive the formula of the spherical cap?

Force Systems in Space

Forces in Space (3D Forces)
Magnitude of a force F in space

$F = \sqrt{{F_x}^2 + {F_y}^2 + {F_z}^2}$

Components of a force in space

$F_x = F \cos \theta_x$

$F_y = F \cos \theta_y$

$F_z = F \cos \theta_z$

Direction cosines

$\cos \theta_x = \dfrac{F_x}{F}$

$\cos \theta_y = \dfrac{F_y}{F}$

$\cos \theta_z = \dfrac{F_z}{F}$

Proportion of components

$\dfrac{F_x}{x} = \dfrac{F_y}{y} = \dfrac{F_z}{z} = \dfrac{F}{d}$

Moment of a force about an axis

Problem 602 | Resultant of Concurrent Forces in Space

Problem 602
Determine the magnitude of the resultant, its pointing and its direction cosines for the following system of non-coplanar, concurrent forces. 300 lb (+3, -4, +6); 400 lb (-2, +4, -5); 200 lb (-4, +5, -3).
 

602-resultant-3d-forces.gif

 

Problem 603 | Resultant of Concurrent Forces in Space

Problem 603
603-resultant-3d-forces.gifDetermine the magnitude of the resultant, its pointing, and its direction cosines for the following system of non-coplanar concurrent forces. 100 lb (2, 3, 4); 300 lb (–3, –4, 5); 200 lb, (0, 0, 4).
 

Problem 604 | Resultant of Concurrent Forces in Space

Problem 604
604-resultant-3d-forces.gifDetermine the magnitude of the resultant, its pointing, and its direction cosines for the following system of non-coplanar concurrent forces. 200 lb (4, 5, –3); 400 lb (–6, 4, –5); 300 lb, (4, –2, –3).
 

Trigonometry: Velocity of belt driving a pulley

Submitted by dhara geecee on July 11, 2015 - 10:34am

I've got this Situation in our trigonometry class and i'm a bit confused.. Here is the math problem: A pulley of radius 6 inches drives a machine by a belt. If the pulley is turning at 300 rev/min, what is the velocity of the belt in feet per minute? Kindly answer with solution, please..

Raymond Ondesimo's picture

ECE Reviewer

Submitted by Raymond Ondesimo on July 13, 2015 - 2:51pm

Who has reviewers here for ECE board exam?

Rexel Reedus's picture

Integral Calculus: Finding the equation of the curve.

Submitted by Rexel Reedus on July 15, 2015 - 12:27am

Hello, can someone help me solve this problem? I tried working it around but I can't arrive at the correct answer. Thank you!

Problem: Find the equation of the curve for which y''=12/x3 if it passes through (1,0) and is tangent to the line 6x+y=6 at that point.

Answer: xy+6x=6

Source: Elements of Calculus and Analytic Geometry by Reyes and Chua

Discussion on: Problem 354 | Equilibrium of Non-Concurrent Force System

Submitted by Renz Anjo Caparas on July 17, 2015 - 10:52am

Following is a discussion on the Reviewer item titled: Problem 354 | Equilibrium of Non-Concurrent Force System.
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zelRach02's picture

thermo

Submitted by zelRach02 on July 17, 2015 - 4:48pm

A spherical container of negligible thickness holding a hot fluid at 1400
and having
an outer diameter of 0.4 m is insulated with three layers of each 50 mm thick
insulation of k1 = 0.02: k2 = 0.06 and k3 = 0.16 W/mK. (Starting from inside). The
outside surface temperature is 300C. Determine (i) the heat loss, and (ii) Interface
temperatures of insulating layers.

need explaination plss..

ladyaira0107@gmail.com's picture

Solid Compound Shaft

Submitted by ladyaira0107@gm... on July 19, 2015 - 4:04am

The solid compound shaft, made of three different materials, carries the two torques shown. (a) Calculate the maximum shear stress in each material. (b) Find the angle of rotation of the free end of the shaft. The shear moduli are 28 GPa for aluminium, 83 GPa for steel and 35 GPa for bronze.

ladyaira0107@gmail.com's picture

Homework About Torsion

Submitted by ladyaira0107@gm... on July 19, 2015 - 4:07am

The solid compound shaft, made of three different materials, carries the two torques shown. (a) Calculate the maximum shear stress in each material. (b) Find the angle of rotation of the free end of the shaft. The shear moduli are 28 GPa for aluminium, 83 GPa for steel and 35 GPa for bronze.

screenshot_2015-07-19-04-01-512.jpg

ladyaira0107@gmail.com's picture

Help please :( - Flange Bolt coupling

Submitted by ladyaira0107@gm... on July 19, 2015 - 9:24am

A flanged bolt coupling consists of two concentric bolt circles. One bolt circle consists of six 0.5-in-diameter steel bolts on a circle 9 inches in diameter and the other consists of eight 0.5-in-diameter steel bolts on a circle 12 inches in diameter. What is the shearing stress in the bolts if a torque of 7 kip-ft is to be carried by the assembly?

Discussion on: 226 - Moment of force about different points

Submitted by QIndustries13 on July 19, 2015 - 3:48pm

Following is a discussion on the Reviewer item titled: 226 - Moment of force about different points.
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Discussion on: 227 - Moment of resultant force about a point

Submitted by QIndustries13 on July 19, 2015 - 3:54pm

Following is a discussion on the Reviewer item titled: 227 - Moment of resultant force about a point.
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period and phase shift of a function

Submitted by dhara geecee on July 26, 2015 - 2:41pm

What is the period of: f(x)=2sin(-3x)
The phase shift of the function: f(x)=2cos(3x-pi)

Manicdao Marlone's picture

Discussion on: Solution to Problem 609 | Double Integration Method

Submitted by Manicdao Marlone on July 29, 2015 - 7:35pm

Following is a discussion on the Reviewer item titled: Solution to Problem 609 | Double Integration Method. Feel free to add your own comments!

Klahrinz William Catubig's picture

Discussion on: Application of Maxima and Minima

Submitted by Klahrinz Willia... on July 29, 2015 - 8:40pm

Following is a discussion on the Reviewer item titled: Application of Maxima and Minima. Feel free to add your own comments!