A normal human being taking a leap maps a path matching a parabola. Skilled ballerinas are able to glide across a stage with head and torso nearly horizontal, giving the appearance of floating across the stage. How ??
The center of mass of the ballerina still moves in a parabola. However the ballerina orients her head to move in a straight path.
A pine board requires about 3 times the strength and energy required to break a concrete block. However it is easier to break a board. Why??
Because the board is much lighter, hence in a given collision it acquires much more velocity for the given fist speed than the far heavier concrete block.
Moderation Team
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