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MEDEFORQUIZ 1

PART 1. (2 pts. each) Multiple Choice.

I Which of the following is true regarding axial stress?A. the deformation is parallel to the action of the forceB. the resisting area is perpendicular to the line of action of the forcec- the resultant force passes thru the centroid of the cross section

@ att of the above2. Which of the following is true regarding shear stresses?

A. the deformation is parallel to the action of the forceB. the resisting area is parallel to the line of action of the force

@ both A and BD. neither A nor B

3. Two rods of the same material and diameter d but one longer than the other are acted upon byequal forces F. Which rod will hav-51the higher strain?A. the longer rod @ will have equal strainB the shorter rod D. cannot be determined

4. Factors of safety are used such that the expected limiting strength of material is not reached thusoreventing failure. What is the factor of safety if the material is allowed to fail?

At1 B=0 c'>1 D'noneofthechoices

5. Which of the following is dimensionless (unitless)?A. Modulus of elasticity C. elongation

D. all of the choices

6. [hich of the following property represents the limiting stress for a ductile material?C. modulus of rigidity@ yield strengthB. ultimate strength D. Poisson's ratio

7. The stress distribution evens out at distances far away from the point of application of the force.This conceot is embodted in(Q St. Venant's principle C, Hooke's LawV. Newton's 2nd'Law D. Poisson's equation

B, The stress-strain relation within the elastfiegion is given byA. St. Venant's prrnciple (/Hooke's LawB. Newton's 2no Law D. Poisson's equation

@ Poisson's ratio

change in temperature?A. bronze C95400 TQ50B. structuralsteel, ASTM 436

10.

A metal bar held between two rigid walls is under tension at temperature T. lf the stress is to bereduced to zero, the bar should fiA. heated B. cooled (} teft atone D. cannot be determined

Forthesituation give4 in#9, which of thefollowing materialof the metal barwill havethe highest

C, titanium allov

@gruy cast iron ASTM A48

PART 2. Problem Solving. SHOW COMPLETE SOLUTION.

1. A 15 mm diameter steel (E = 200 GPa) rod (2) is connected to a 25 nrm wide byrectangular aluminum (E = 70 GPa) bar (1), as shown. The bolt at C (red brass, Ehas a diameter of 10 mm and is under double shear' Determine:

a. the force P required to stretch the assembly by '10 mmb. the normal stress In each barc. the shear stress in the bolt at C

10 mm thick= 1'15 GPa)

/,/

2. pipe (1), made of bronze (E = 110 GPa), with a cross sectional area of 4000 mm'is connectedto pipe (2), made of steel (E = 200 Ce5;, witn a cross sectional area of 2000 mm2 through the

ftange ai e. lt the support ain *itl yield to'the right (will move to the right) by 1.5 mm, determine:a. Normal stresses in pipe (1). ls it tensile or compressive?b. Normal stress in pipe (2). ls it tensile or compressive?

4.0 m 6.0 mr"-"-- -"'*'"7

3. A high-density potyethytene IE = 830 MPa; s= 140 x 10-6/"C] block (1)is positio_ned in a fixtureas shown. The block has an area of At = 1 600 mmz and a length of L1 = 760 mm At roomtemperature, a gap of a = 5 mm exists between the block and the rigid support at B. Determine:

(a) the normal stress in the block caused by a temperature increase of 55"C.(b) the normal strain in block (1) at the increased temperature'

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