A See-Saw Will Balance When the Pivot Is Placed at the Center

question 48

Multiple Choice

A see-saw will balance when the pivot is placed at the center of mass of the system.If a boy and his brother sit at distances 3L and L from the pivot,respectively,and the see-saw is balanced,what is the boy's mass if his brother's is 85 kg? Assume the see-saw board is uniform.

• A)28 kg
• B)64 kg
• C)21 kg
• D)57 kg

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Definitions:

Red Blood Cells

These cells carry oxygen from the lungs to the body's tissues and return carbon dioxide from the tissues back to the lungs.

Bursal Fluid

The lubricating fluid found within bursae, small sacs located near joints that reduce friction between bones and soft tissues.

Epiphyseal Plate

A hyaline cartilage plate in the metaphysis at each end of a long bone, where growth in length occurs.

Bursae

Small fluid-filled sacs located between bones and soft tissues, acting as cushions to reduce friction and allow free movement.