A person of mass $$70kg$$ jumps from a stationery helicopter with the parachute open .As he falls through $$50m$$ height, he gains a speed of $$20ms-1$$. .The work done by the viscous air drag is

Question

A person of mass $$70kg$$ jumps from a stationery helicopter  with the parachute open .As he falls through $$50m$$ height, he gains a speed of $$20ms-1$$. .The work done by the viscous air drag is

Infinity Learn · Accepted Answer

From $$work-energy$$ theorem, net work done by all the forces (internal$$ and external $$) $$=$$ change in kinetic energy ⇒Work done by gravity $$+$$ Work done by air drag $$=$$ change in kinetic energy.            Kinetic energy gained      $$=$$ $$12$$ × $$70(202-02)=14000Potential$$ energy lost $$=$$ $$mgh$$ $$=$$ $$70(10)50$$ $$=$$ $$35000$$⇒Work done by air drag $$=$$ $$KE_PE=14000-35000$$ $$=$$ $$-$$ $$21000J$$

A person of mass 70kg jumps from a stationery helicopter with the parachute open .As he falls through 50m height, he gains a speed of $20 m s^{- 1} .$ .The work done by the viscous air drag is

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A person of mass 70kg jumps from a stationery helicopter with the parachute open .As he falls through 50m height, he gains a speed of 20ms-1. .The work done by the viscous air drag is

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A person of mass 70kg jumps from a stationery helicopter with the parachute open .As he falls through 50m height, he gains a speed of $20 m s^{- 1} .$ .The work done by the viscous air drag is