Answer:
the resulting angular acceleration is 15.65 rad/s²
Explanation:
Given the data in the question;
force generated in the patellar tendon F = 400 N
patellar tendon attaches to the tibia at a 20° angle 3 cm( 0.03 m ) from the axis of rotation at the knee.
so Torque produced by the knee will be;
T = F × d⊥
T = 400 N × 0.03 m × sin( 20° )
T = 400 N × 0.03 m × 0.342
T = 4.104 N.m
Now, we determine the moment of inertia of the knee
I = mk²
given that; the lower leg and foot have a combined mass of 4.2kg and a given radius of gyration of 25 cm ( 0.25 m )
we substitute
I = 4.2 kg × ( 0.25 m )²
I = 4.2 kg × 0.0626 m²
I = 0.2625 kg.m²
So from the relation of Moment of inertia, Torque and angular acceleration;
T = I∝
we make angular acceleration ∝, subject of the formula
∝ = T / I
we substitute
∝ = 4.104 / 0.2625
∝ = 15.65 rad/s²
Therefore, the resulting angular acceleration is 15.65 rad/s²
When looking at this question, we can easily start by eliminating certain answers. In the selections you've provided, you've shown atmosphere. We can easily eliminate letter A, as that makes absolutely no sense. Moving on, you also eliminate letter B, as that deals with ecosystems and whatnot. And finally, you can eliminate hydrosphere, letter C - as that's not the same. That deals with water, like oceans or rivers.
That leaves you with D) Lithosphere for your answer. The Lithosphere is the rigid part of the earth, the outermost layer, I would say. The crust / mantle. That's why it would be letter D - plate tectonics seem to have relations with the Lithosphere. The lithosphere is affected.
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Yes, in general, metalloids are slightly reactive.
