Question

stone of mass 3kg is droped from top of a building 25m high on a heap of sand penetrate 0.5m deep in sand . calculate retarding force exerted by sand on stone

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Answer 1

Final Velocity(when it falls on ground)

= √(2gh)

= 10√5 m/s

Now, using 3rd equation of motion,

$\therefore \:0 = {(10 \sqrt{5}) }^{2} - 2 \times a \times 0.5 \\ \implies \: 500 = a \\ \\ \implies \: Retarding \: force \: exerted \: by \: sand \: is \: 500 \frac{m}{s}$