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DANVILLE COMMUNITY COLLEGE SUMMER 2012

EGR 140 Engineering Mechanics Statics

Midterm Exam (280 points)

Prepared by Dr. Yiheng Wang (ywang@dcc.vccs.edu), 06/18/2012

Dear Proctor,

I sincerely appreciate the help you offer to the students in class EGR 140 Engineering

Mechanics Statics at Danville Community College. Here are some guidelines for this

midterm exam:

1. Please check the students photo ID before allowing them to take the exam.

2. This is a closed-book, closed-notes, paper-based exam. No formula sheet of any kind is

allowed. Only scientific calculator, necessary stationary and extra plain paper is

permitted. After completing the exam, please do not allow the student to take any notes

back from the exam.

3. The permitted time for this exam is 2 hours.

4. After the students completion of this exam, you can send it back using one of the three

methods:

a) Through email: please scan the entire exam and email it back to me at:

ywang@dcc.vccs.edu, AND the DCC testing center at:

dcctestingcenter@dcc.vccs.edu;

b) Through fax: please fax the entire exam to DCC testing center ONLY, at: 434-797-

8415;

c) Through regular mail: please mail the entire exam to DCC testing center ONLY,

at: Danville Community College, Learning Assistant Center, 1008 South Main

Street, Danville, VA 24541.

5. After you have sent the test back by fax or by regular mail, please send me an email at

ywang@dcc.vccs.edu so that I know when and how I should expect the exam. I expect

to receive the test no later than Friday, June 22nd

by 12:00 noon.

Thank you very much, and please feel free to contact me if you have any questions.

Sincerely,

Yiheng Wang, Ph.D.

Assistant Professor of Engineering

Danville Community College

Email: ywang@dcc.vccs.edu

Office Phone: 434-797-8435

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Please show ALL necessary steps in your work!

1. The guy wires are used to support the post. Solve the following problems. Neglect the

dimension of the post.

(a) Express FB and FD in vector format respectively. (30 points)

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(b) Determine the projection of force FB along segment CD. (20 points)

(c) Determine the moment produced by force FB about the OD axis. (20 points)

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2. Handle forces F1 and F2 are applied to the electric drill.

(a) Find the resultant force FR (in vector form) of F1 and F2 and determine the coordinate

direction angles of FR. (20 points)

(b) Determine the total moment caused by F1 and F2 about point O. Express the result in

vector form. (30 points)

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3. If cylinder F weighs 50 lb and = 10, determine the weight of cylinder E. Separate free-

body diagrams of ring B and ring C must be included and will be graded. (40 points)

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4. If the tension force in each of the cables AB, AC and AD cannot exceed 1.2 kN, determine the

maximum mass of the flowerpot. Set x = 2 m and z = 1.5 m. Free-body diagram of point A

must be included and will be graded. (40 points)

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5. Determine the horizontal and vertical components of reaction at the pin A and the reaction in cable

BC. Free-body diagram of the rigid body must be included and will be graded. (The thickness

of the pole is negligible.) (40 points)

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6. Determine the reactions at the single journal bearings A, B and C. The magnitudes of the two forces

are F1 = 450 N and F2 = 600 N. (40 points)