KINE-1800_Assignment 4_F21© 2021 – Dr. Nadia Azar 1 KINE-1800 Fundamental Mechanics of Human...

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KINE-1800_Assignment 4_F21© 2021 – Dr. Nadia Azar 1 KINE-1800 Fundamental Mechanics of Human Movement ASSIGNMENT #4 6% of Final Grade DUE by 4:00 PM on Friday, November 19, 2021Total out of 19 Marks: _________________________Name: ________________________________________                   Student ID#: __________________________________Partner’s Name: ________________________________________                   Partner’s Student ID#: __________________________________ASSIGNMENT INSTRUCTIONS: • You may complete this assignment alone or with ONE other student o If you work with a partner, please include both of your full names and student numbers in the spaces provided. Only ONE of you will upload the assignment in Blackboard. • Please do not type your answers (text or calculations). Instead: i. Print a copy of this document and hand write your answers in the spaces provided. ii. When you are finished the assignment, scan each of the pages using the native scanning function on your phone or a document scanning app (e.g., Adobe Scan, CamScanner). Please do NOT submit photos of your assignment. iii. Save the scan as a PDF document (make sure all the pages are in a single PDF document!) iv. Upload and submit the PDF of your assignment through Blackboard • For questions involving calculations: o Make sure you show ALL the steps that lead to your final answer. No steps shown, no marks given.  o For multi-step calculations, cay two (2) decimal places through your calculations o Express your final answers to two (2) decimal places and include the proper units. • Please see the assignment submission portal in Blackboard for detailed instructions on when and how to submit your assignment  This assignment and it’s marking key are the intellectual property of Dr. Nadia Azar and are protected by copyright laws.  Reproduction or dissemination of this assignment in any manner whatsoever is strictly prohibited. Students who violate this rule or engage in any other form of academic dishonesty will be subject to disciplinary action under Senate Bylaw 31: Academic Integrity and may be subject to other legal action.© 2021 – Dr. Nadia Azar 2 Question 1 [4 marks]. During a flip, a gymnast can manipulate their angular velocity even though no external moments are applied to their body. For example, their angular velocity as they land is much less than their angular velocity during the tuck portion of the flip. Which mechanical property does the gymnast purposefully manipulate to decrease their angular velocity as they land, and how do they do it?                Question 2 [4 marks]. Based what you know about the factors that contribute to an object’s stability, explain why an elderly person might have more difficulty getting up out of a low, deep chair than getting up out of a standard-height chair?               © 2021 – Dr. Nadia Azar 3 Question 3 [4 marks]. A person performs a bent-over lateral cable raise and hold the position shown in the image to the right (assume the upper limb is fully extended and parallel to the ground). A free-body diagram of the forces acting on the upper arm and their moment arms has been provided. i. What is the magnitude and direction of the net moment caused by the weight of the upper arm (W) and the tension in the cable (T)? ii. How much force must the deltoid muscle generate (FD) to hold the upper arm stationary in this position?                             "File:Bent-over-cable-lateral-aises-1.png" by Everkinetic is licensed under CC BY-SA 3.0.   © 2021 – Dr. Nadia Azar 4 Question 4 [4 marks]. You start at t = 0 s with your knee fully extended (see figure), and then you flex your knee until the lower leg stops when it is vertical at t = 4.0 s. The mass of the lower leg is 3.78 kg and its radius of gyration is 0.24 m. The angular position and velocity at t = 2.2 s are shown in the figure.   i. Calculate the average angular impulse from t = 0 s through t = 1.23 s. [2 marks]. ii. Calculate the magnitude and direction of the net moment t = 0 s through t = 1.23 s. [1 mark]  iii. Using the angular analog to Newton’s 2nd Law, calculate the average angular acceleration of the lower leg from t = 0 s through t = 1.23 s. [1 mark]                       t = 0 s θ = 0 rad ω = 0 rad/s t = 1.23 s θ = -0.79 rad ω = -1.28 rad/s t = 4.0 s θ = -1.57 rad ω = 0 rad/s © 2021 – Dr. Nadia Azar 5 Question 5. [3 marks]. Give an example of a short answer question you think would make a great question on an exam and provide the coect answer for it. This could be either a text/theory question or a calculation.  Question = 1 mark, coect answer to the question = 2 marks

Ravindra Kumar · Accepted Answer

Question 1
During a flip, a gymnast can manipulate their angular velocity even though no external moments are applied to their body. For example, their angular velocity as they land is much less than their angular velocity during the tuck portion of the flip. Which mechanical property does the gymnast purposefully manipulate to decrease their angular velocity as they land, and how do they do it?
Solution
During the flip, gymnast used to manipulate their angular velocity because we know that the angular momentum always be conserve if any external force is not getting apply on it.
Let the mass of the gymnast be m, initial moment of inertia be  and let he is rotating with  angular velocity then his initial angular momentum will be 
But when he flipped his body then his moment of inertia gets change, then due to changing of the moment of inertia of the body, his angular velocity will also get change.
Applying the conservation of angular momentum
Here, new angular velocity of the body be and new moment of inertia of the body becomes .
So, we can conclude that gymnast is changing the moment of inertia of the body by opening his hand and legs, due to which angular velocity of the body is also getting change.
Question 2
Based what you know about the factors that contribute to an object’s stability, explain why an elderly person might have more difficulty getting up out of a low, deep chair than getting up out of a standard-height chair?
Solution
As we know that elderly person has the higher length (height) than the younger person. Due to which the centre of mass of the elder person used to be at bigger hight than the younger person’s height. So, when the elder person sit into the deep chair with respect to the normal standard chair his body’s centre of mass goes to much lower height. It means, elder person, when he was in standing position have higher potential energy.

KINE-1800_Assignment 4_F21 © 2021 – Dr. Nadia Azar 1 KINE-1800 Fundamental Mechanics of Human Movement ASSIGNMENT #4 6% of Final Grade DUE by 4:00 PM on Friday, November 19, 2021 Total out of 19...

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