The diagram represents speed-time for a sky diver. He falls freely
from an aircraft then opens a parachute and later lands safely on the
ground. At which point did the parachute fully open?
It's also not drawn quite right at the end. The speed definitely does not increase at any point after B.
My guess was B but it turned out to be C.
The answer presented:
The sky diver is falling under gravity known as free-falling at the
beginning. The speed of the sky diver increases with time with
decreasing acceleration till point B. The speed decreases when the
parachute opens at point B. The parachute fully opens at point C.Note: This questions ask (sic) which point did the parachute fully
opened (sic), not when did the parachute just opened, (sic) which is
point B.
Questions:
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In what way does a parachute not "fully" open?
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Is C necessarily THE point between B and D wherein the parachute fully opens? I was thinking C is merely the closest answer among A, B, C and D.
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Why does the diver speed up at a decreasing rate? Since the acceleration due to gravity is constant, I was thinking that the diver speeds up constantly.
Best Answer
The parachute can not be opened instantaneously.
The parachute is fully opened at the "vinicity" of the point $C$.
The acceleration due to gravity is constant but there is another force one needs to take into account : the air resistance.