HKIN 298 TWU Biomechanics Torque Levers Balance and Stability Assignment the course is for biomechanics based on textbook called applied biomechanics conce

HKIN 298 TWU Biomechanics Torque Levers Balance and Stability Assignment the course is for biomechanics based on textbook called applied biomechanics concepts and connections chapter 6, chapter 8 and chapter 7please make sure to used full sentences, show all the work and explain the reasoning HKIN 298 Biomechanics
Chapter 6/8 Torque and Levers. Chapter 7 Balance and Stability. Questions. (21.5marks)
Please type directly into the MS Word doc in BOLD script, please. Use full sentences. For
calculations, show your work.
1. Two athletes perform shoulder dumbbell raises (arms straight from the side, abducted to 90 degrees)
with 15 lb dumbbells. One athlete has much longer arms than the other.
Explain biomechanically why the shoulder raise for the athlete with the longer arms demands more
muscular force than for the athlete with shorter arms as he rotates his arms to 90 degrees to the ground.
(2 marks)
2. Describe fully what the two key functions of levers are (2 marks).
3. Two children wish to balance on a 2.5 m long teeter-totter. One child has a weight force of 80N and sits
1.6m from the axis. The other child has a weight force of 90N. How far from the axis does the second child
have to sit from the axis to balance the teeter-totter? Show your work (1 mark)
4. The length-tension relationship is in (skeletal) muscle helps us understand force variation in human
muscle across a range of motion. In a couple of sentences, describe the length-tension concept in your
own words (2 marks)
5. With respect to the length-tension relationship in muscles, explain what ‘active insufficiency’ is (1 mark)
6. The following diagram shows a series of base of supports (1-3), each receiving an external force (A and
B). Which of the following base of supports would be the most stable and least stable receiving:
1. External force A?
2. External force B?
E.g. BOS 1 would be most stable receiving force ___ because….but least stable receiving force ____
because…
Give a reason for your answer (2 marks)
7. The following is a graph of the force velocity relationship. In your own words (don’t copy and paste from
the powerpoint) describe briefly what this relationship is (2 marks)
8. In the following diagram if the motive force was 40N and the motive force arm was 0.3m and the resistive force
was 10N and the resistive force arm was 0.8m, calculate the net torque and direction of this system. Show your work
(1 mark)
.
Motive force
Resistive force
9. For the following diagram label each position from least stable to most stable using the following anchors: (2
marks)
1 = least stable
2 = somewhat stable
______
3 = more stable
_______
4 = most stable
_______
______
10. Label each of the following diagrams as either 1st class lever, 2nd class lever or 3rd class lever (1.5
marks)
Where M = motive force, R = resistive force and A = axis
____________________
_____________________
_____________________
11. The following is a diagram of a knee extension exercise showing the femur (solid triangle), knee joint or
axis (solid dot), kneecap (oblong circle) and two positions of the lower leg (A – beginning extension and B –
end of extension). The dotted line arrows represent the lines of resistive weight force of the lower leg at
positions A and B. The solid arrow represents the average location of the line of motive muscle force
exerted by the quadriceps muscle as the lower leg moves from position A to B.
Answer the following questions:
(a.) Describe the differences between the average muscle motive force arm and the resistive force arms of
the lower leg. What changes to the size of the resistive and motive force arms do you see occurring as
the lower leg moves from position A to position B (towards full extension)? (2 marks)
(b.) The resistive force of the lower leg is 100N. The size of the resistive force arm at A is 0.1m and at B it
is 0.22m. If the average muscle force arm is 0.02m, calculate the amount of muscle force needed to rotate
the lower leg at both A and B. (1 mark).
B
A
12. Why is it more difficult to open a door as you push closer to the hinges compared to further away from
the hinges? Describe how the lever models change as you move points of force application closer to the
hinge (axis). Does the resistive torque change as force is applied closer to the axis? Why or why not? (2
marks)

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