UNIVERSITY ENGINEERING EXAMINATIONS/ Assignment 2025
AEM2601
Engineering Dynamics
Welcome to the AEM2601 Assignment
Date: 6 May 2025
Time: 00:00 – 24:00
Hours: 24
Examiner name: Mr V Ramnath
Internal moderator name: Prof H Ngwangwa
External moderator name: Prof D Desai
This paper consists of 2 pages.
Total marks: 100
Number of pages: 2
Instructions:
 In this assessment every student will have different values in their respective calculations
based on their unique Unisa 8-digit student number which is used to work out a random value
𝑟 such that the value of 𝑟 is a pure number such that 0 < 𝑟 < 1 that is in between zero and
unity where the formula of the random value is determined from the following formula:
Random value: r = 0.25 + (10 ∙ 𝑆) where 𝑆 is the 8-digit student number
Example: 𝑆 = 41238562 therefore 𝑟 = 0.25 + 0.41238562 = 0.66238562
 This assessment is on the myUnisa Moodle platform and uses a file upload tool.
 Students must submit their work in an engineering report with a single uploaded Adobe PDF
file on the myUnisa Assessment 1 shell. Students must make sure to type their 8-digit Unisa
student number in their engineering report and include any appendices of computer code
and all supporting calculations for completeness and thoroughness.
Additional student instructions
1. Students must upload their answer scripts in a single PDF file (answer scripts must not be
password protected or uploaded as “read only” files)
2. Incorrect file format and uncollated answer scripts will not be considered.
3. NO emailed scripts will be accepted.
4. Students are advised to preview submissions (answer scripts) to ensure legibility and that
the correct answer script file has been uploaded.
5. Incorrect answer scripts and/or submissions made on unofficial examinations platforms
(including the invigilator cell phone application) will not be marked and no opportunity will
be granted for resubmission. Only the last answer file uploaded within the stipulated
submission duration period will be marked.
6. Mark awarded for incomplete submission will be the student’s final mark. No opportunity for
resubmission will be granted.
7. Mark awarded for illegible scanned submission will be the student’s final mark. No
opportunity for resubmission will be granted.
8. Submissions will only be accepted from registered student accounts.
9. Students suspected of dishonest conduct during the examinations will be subjected to
disciplinary processes. Plagiarism is a violation of academic integrity and students who
plagiarise, copy from published work or Artificial Intelligence Software (e.g., ChatGPT) or
online sources (e.g., course material), will be in violation of the Policy on Academic
Integrity and the Student Disciplinary Code and may be referred to a disciplinary hearing.
Unisa has a zero tolerance for plagiarism and/or any other forms of academic dishonesty.
10. Non-adherence to the processes for uploading assessment responses will not qualify the
student for any special concessions or future assessments.
Question 1
Kinetics of particles is considered as the study of forces on particles and the accelerations that result on the
particles due to the influence of these forces. The specification of forces and accelerations may in turn be
utilized to determine the displacement and velocity of the resultant motions. These concepts are discussed in
the prescribed textbook by Hibbeler in Chapter 13. To solve these types of problems one essentially specifies
the vectors of forces (magnitudes and directions) on a free body diagram, applies vector superposition to
determine the resultant force (on the centre-of-mass), and then applies Newtons second equation of motion
which produces a governing differential equation of motion that models the kinetics (forces/acceleration) of the
mechanical system.
Consider a car with an initial zero displacement of mass 𝑟 × 12600 kg that is travelling at a slow velocity of
𝑟 × 124.7 km/hr that is subjected to a wind drag force that is proportional to the velocity of the car with a
constant of proportionality of ‖𝑙𝑛(𝑟)‖ × 0.587. The rolling friction between the car and the road may be
approximated with a constant coefficient of friction of 𝑟 × (0.27) by neglecting the dynamic coefficient of
friction which varies with velocity for simplicity. It may be assumed that the gravitational acceleration constant
is 𝑔 = 9.81 m.s -2 and that the car travels on a flat horizontal surface that does not have any incline.
Determine the distance and time the car will travel before its velocity becomes 𝑟 × 𝑣 .
HINT: For this assessment the differential equation may be solved with the computational intelligence tool
Wolfram|Alpha that is accessible from the following website
https://www.wolframalpha.com/
This question is adapted from Hibbeler Chapter 13 Problem 13.36 page 135 and basically tests if students can
understand and apply the Newton’s equations of motion. It involves the solution of a differential equation (which
can be solved with Wolfram|Alpha) and it also involves the solution of simultaneous linear equations. Think
about what are the two equations at the initial state of motion.
[50]
Question 2
Consider a 22.3 kg block on a horizontal surface where the block has an initial velocity of 𝑟 × 7.3 m.s -1. A
variable force that varies with the distance that the block is displaced has a magnitude of ‖ln(𝑟)‖ × 72.3 𝑠 N
that is applied to the block so that it slides across the horizontal surface towards the right. The mechanical
system does not exhibit any frictional forces for simplicity. Determine the distance the block slides across the
surface such that the final velocity is larger by a multiplicative factor of (1 + 𝑟) than that of the initial velocity.
Explain with appropriate reasoning whether you think it is possible to determine the corresponding time for the
block to reach this increased velocity and if so how this could be done (you are allowed to use a mixture of
equations, graphs and explanations).
HINT: This problem is adapted from Hibbeler Chapter 14 Problem 14.11 page 197 and basically tests if
students understand the principles of work and energy and how it can be used to understand mechanical
systems and derive governing equations of motion.
[50]
TOTAL MARKS: 100
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