Moving oneself when in freefall?

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In free fall, such as during jumping or trampolining, individuals experience apparent weightlessness, making it easier to move limbs compared to standing still. While it may seem that moving arms horizontally in free fall is effortless, it still requires effort because the gravitational force on the arms remains constant. Although muscles do not need to counteract their weight in free fall, extending arms from a relaxed position still involves work against inertia. The absence of a normal force means one does not feel their weight, but lifting limbs still creates a normal force relative to the body's position. Thus, while movement may feel easier, it still requires physical effort.
pivoxa15
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Here is an extract from a textbook.

"While jumping or diving or on a trampoline a person will experience apparent weightlessness for a very short time. They will be in 'free fall'. It is much easier in these conditions to move your arms and legs since the force of gravity does not need to be overcome. Standing still and holding your arms out horizontally can be very tiring but a diver or gymnast in motion can move their limbs easily."

Is this correct? Moving ones arms out horizontally when in free fall while trampolining is just as difficult as when standing on the ground because the graviational force on your arms is constant when in free fall or not near the earth.
 
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Yes, it's right. When in free-fall, your muscles are not exerting to keep your arms up against their weight; they are allowed to fall.
 
But you are purposely extending your arms out from a relxed, dangled position. It's like trying to lift a weight a height d while in free fall relative to you. You still have to do work=Fd in lifting this weight. However, I agree you will not feel your own weight because there is no normal force in this situation. However, when lifting (relative to you) whether a weight or your arms, you create the normal force.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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