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Question
A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is ______.
Options
constant and equal to mg in magnitude.
constant and greater than mg in magnitude.
variable but always greater than mg.
at first greater than mg, and later becomes equal to mg.
Solution
A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is at first greater than mg, and later becomes equal to mg.
Explanation:
When the man is squatting on the ground he is tilted somewhat, hence he also has to balance frictional force besides his weight in this case.
R = reactional force = friction + mg
⇒ R > mg
When the man gets straight up in that case friction ≈ 0
⇒ Reactional force ≈ mg
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