es1022ymidtermdecember2013withfinalanswers

8/10/2019 ES1022yMidtermDecember2013WithFinalAnswers

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THE UNIVERSITY OF WESTERN ONTARIO

FACULTY OF ENGINEERING

DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING

ES 1022Y – ENGINEERING STATICS

MID-TERM EXAMINATION

December 17, 2013 (7:00-9:00 PM)INSTRUCTORS: A.D. BINNS / C.A. MILLER

Closed Book

The only external aid allowed is a non-programmable electronic calculator.

Notes:

1. There are four questions.2. Each question is worth 15 marks for a total of 60 marks.

3. This exam is worth 25% of the final mark for the course.

4. Each question is worth 6.25% of the final mark for thecourse.

5. Draw proper free body diagrams as required.

6. Show all steps and calculations clearly.

7. Specify all units with proper prefixes.

8.

Give all final answers to 3 significant figures asappropriate.

9. Answer all questions in the space provided.10. Indicate if answers are continued on the extra pages

provided.

11. Marks will be deducted for poor diagrams and presentation.12. If you believe that information needed to answer a question is missing, make an assumption and

state it clearly, before carrying on.

13. Proctors are not allowed to answer any exam-related questions.

University policy states that cheating, including plagiarism, is a scholastic offence. The

commission of a scholastic offence is attended by academic penalties, which mightinclude expulsion from the program. If you are caught cheating, there will be no second

warning.

Cell phones, blackberries, or personal electronic communications devices are not

allowed on your person or examination desk during the exam.

Question Mark

1 / 152 / 153 / 154 / 15

Total Mark / 60



ES 1022Y – ENGINEERING STATICS – MID-TERM EXAMINATION

December 17, 2013 (7:00-9:00pm)

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2

Question 1

Force F has a magnitude of 50 lbs. Calculate:

a)

The coordinate direction angles of force F. b) The moment due to force F about point C .

c) The component of this moment about the

axis CB, which lies in the x- y plane.

B




December 17, 2013 (7:00-9:00pm)

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3

Question 1 (cont.)




December 17, 2013 (7:00-9:00pm)

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4

Question 2

A crate is supported by cables AC and AB, and

strut AD as shown.

a) Calculate the angle between cables AC and

AB.

b) If the maximum allowable tension in either

cable AC or cable AB is 300 lb, determine the

largest weight of the crate that can be

supported without exceeding this value in

either cable.

c) What is the corresponding force developed

along strut AD for this weight of the crate?




December 17, 2013 (7:00-9:00pm)

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5

Question 2 (cont.)




December 17, 2013 (7:00-9:00pm)

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Question 3

A boy stands out at the end of the diving board,

which is supported by two springs at A and B.Each spring has a stiffness of k = 15 kN/m. In the

position shown, with the boy standing at the end,

the board is horizontal. Neglect the weight of the board and assume it is rigid. If the boy has a mass

of 40 kg:

a) Calculate the reaction forces developed at A

and B.

b) State whether each spring is acting in tension

or compression.

c)

Determine the angle of tilt which the boardmakes with the horizontal after the boy jumpsoff.




December 17, 2013 (7:00-9:00pm)

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7

Question 3 (cont.)




December 17, 2013 (7:00-9:00pm)

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8

Question 4

A beam is loaded as shown. Replace the loading

by a single equivalent force that has the sameeffect as the loading shown, and specify the

location of the point that this force acts on the

beam measured from point O.




December 17, 2013 (7:00-9:00pm)

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9

Question 4 (cont.)




December 17, 2013 (7:00-9:00pm)

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11

Additional Blank Page




December 17, 2013 (7:00-9:00pm)

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Additional Blank Page



Question 1:

a) Coordinate direction angles are α = 73.4o, β = 64.6

o, γ = 149

o

b) Moment due to force F about point C is {-1930i + 429 j – 429k} lb.ft

c) Component of this moment acting about axis CB is -1060 lb.ft

Question 2:

a) The angle between cables AC and AB is 36.7 degrees

b) W = 407 lb (largest weight of the crate that can be supported)

c) Force developed along strut AD FAD = 557 lb (directed towards point A)

Question 3:

a) Reaction force at A, FA = 1.18 kN (directed down); reaction force at B, FB = 1.57 kN

(directed up)

b)

Spring at A is in tension; spring at B is in compressionc) Angle of tilt the board makes with the horizontal after the boy jumps off is 10.4 degrees

Question 4:

Equivalent force is 51 kN (directed down) acting at a point 17.9 m to the right of point O.

es1022ymidtermdecember2013withfinalanswers

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