Question

17,18,19 and 20

17) Which statement about the centre of mass (COM) of a segment is incorrest? b) You need to know the location of the segment COM (relative to the joint axis) to determine the c) The СОМ is typically measured front the proximal end of the segment The segment COM cannot be determined based on an individuar right 18) Given muscle forces A and 8 that are equal in magnitude and act at the hip joint, what is the direction of the corresponding joint reaction force? a) Up and to the right b) Down and to the right O To the left to zero ω The linear or angular motion of an object is changing 20) Given the horizontal ground reaction force for walking shown to force 1- za

Answer 1

17.

we absolutely need the length of the segment to calculate the COM as we need the know the distribution.

if we know COM we can easily apply solve a problem by assuming an equivalent body there having same weight so it helps in torque as well

it is calculated from end so to keep it standard.

so only option which is not true is D

Also see it does not matter what is the height as it will not change the distribution of particles across the length

SO answer is D

18.

we can see both forces A and B cancels each other in the vertical direction

so net force remains in the horizontal direction only.

so to balance it joint reaction force has to be in the opposite direction i.e. left

so answer is C

19.

An object in static equilibrium is unable to move because all the forces acting on it compensate for one another.

so this takes out option a,c,d.

now think like this also if linear or angular motion is changing it means there is acceleration on body . If there is acceleration then there is force so it means it is not in equilibrium.

so option B

20.

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As you can see in the picture net force during walking. you can see that the negative force in the second diagram(towards the left ). so it means maximum negative will be at some point when your feet is at supported at your ankle and will be towards left.this force will always stop you from going forward so it will be the maximum braking force

so answer is option A