A ball of 10kg falls from rest from a height of 150m, Neglating air resistance, calculate its kinetic energy after falling a distance of 40m

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1. Answer: [tex]3920\ J[/tex]

   Explanation:

   Given

   mass of ball m=10 kg

   It is placed at a height of 150 m

   It is dropped from the height and allowed to free fall for 40 m

   Velocity acquired by the ball during this fall is given by [tex]v^2-u^2=2as[/tex]

   Insert u=0, a=g

   [tex]\Rightarrow v^2-0=2\times 9.8\times 40\\\Rightarrow v=\sqrt{784}\\\Rightarrow v=28\ m/s[/tex]

   Kinetic energy at this instant

   [tex]K.E.=\dfrac{1}{2}\times 10\times 28^2\\\\\Rightarrow K.E.=3920\ J[/tex]

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