Problem 919 | Additional Axial Compression Load for the Section to Carry No Tensile Stress

Problem 919
From the data in Prob. 918, what additional load applied at the centroid is necessary so that no tensile stress will exist anywhere on the cross-section?
 

Solution 919

Problem 918 | Stress at Each Corner of Eccentrically Loaded Rectangular Section

Problem 918
A compressive load P = 12 kips is applied, as in Fig. 9-8a, at a point 1 in. to the right and 2 in. above the centroid of a rectangular section for which h = 10 in. and b = 6 in. Compute the stress at each corner and the location of the neutral axis. Illustrate the answers with a sketch.
 

figure_9-8a_eccentrically_loaded_column.jpg

 

Eccentrically Loaded Short Compression Member

Consider the cross-section below. A compressive load P is applied at any point (ex, ey) with respect to the principal axes x and y. The moment of P about these axes are respectively
 

$M_x = Pe_y$     and     $M_y = Pe_x$

 

figure_9-9a_eccentrically_loaded_section.jpg

 

Dimensions of the Lot for a Given Cost of Fencing

Problem
A rectangular waterfront lot has a perimeter of 1000 feet. To create a sense of privacy, the lot owner decides to fence along three sides excluding the sides that fronts the water. An expensive fencing along the lot’s front length costs Php25 per foot, and an inexpensive fencing along two side widths costs only Php5 per foot. The total cost of the fencing along all three sides comes to Php9500. What is the lot’s dimensions?

A.   300 feet by 100 feet C.   400 feet by 200 feet
B.   400 feet by 100 feet D.   300 feet by 200 feet

 

Amount of Sales Needed to Receive the Desired Monthly Income

Problem
A salesperson earns \$600 per month plus a commission of 20% of sales. Find the minimum amount of sales needed to receive a total income of at least \$1500 per month.

A.   \$1500 C.   \$4500
B.   \$3500 D.   \$2500

 

The Tide in Bay of Fundy: The Depths of High and Low Tides

Problem
The tide in Bay of Fundy rises and falls every 13 hours. The depth of the water at a certain point in the bay is modeled by a function d = 5 sin (2π/13)t + 9, where t is time in hours and d is depth in meters. Find the depth at t = 13/4 (high tide) and t = 39/4 (low tide).

  1. The depth of the high tide is 15 meters and the depth of the low tide is 3 meters.
  2. The depth of the high tide is 16 meters and the depth of the low tide is 2 meters.
  3. The depth of the high tide is 14 meters and the depth of the low tide is 4 meters.
  4. The depth of the high tide is 17 meters and the depth of the low tide is 1 meter.

 

Longest Day of the Year: Summer Solstice

Problem
The number of hours daylight, D(t) at a particular time of the year can be approximated by
 

$D(t) = \dfrac{K}{2}\sin \left[ \dfrac{2\pi}{365}(t - 79) \right] + 12$

 

for t days and t = 0 corresponding to January 1. The constant K determines the total variation in day length and depends on the latitude of the locale. When is the day length the longest, assuming that it is NOT a leap year?

A.   December 20 C.   June 20
B.   June 19 D.   December 19

 

What is the Chance of Rain: Local vs Federal Forecasts

Problem
The local weather forecaster says “no rain” and his record is 2/3 accuracy of prediction. But the Federal Meteorological Service predicts rain and their record is 3/4. With no other data available, what is the chance of rain?

A.   3/5 C.   1/6
B.   1/4 D.   5/12

 

Find the term independent of x in the expansion of a given binomial

Problem
Find the term that is independent of x in the expansion of $\left( 2 + \dfrac{3}{x^2} \right)\left( x - \dfrac{2}{x} \right)^6$.

A.   180 C.   -140
B.   160 D.   -160

 

Survival Probability Of The 6th Fly that Attempt To Pass A Spider

Problem
A spider eats three flies a day. Until he fills his quota, he has an even chance of catching any fly that attempts to pass. A fly is about to make the attempt. What are the chances of survival, given that five flies have already made the attempt today?

A.   1/2 C.   3/4
B.   1/4 D.   2/3

 

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