Question

A stone of mass 5kg fall from a cliff of 50 m, height buries 1m in sand. Find average resistance offered by
sand and time of penetration.​

Answer 1

Answer:

Explanation:

m = 5 kg

h = 50 m

velocity = v just before hitting the ground 

 v² = u² + 2 g h = 0 + 2 * 9.8 * 50 = 980

When the stone is penetrating the sand:

v² = u² + 2 a s

0 = 980 + 2 * a * 1

a = - 490 m/s²

Average resistance Force offered by sand = m a = - 5 * 490

  =- 2, 450 N

Answer 2

Explanation:

m = 5 kg

h = 50 m

velocity = v just before hitting the ground

v² = u² + 2 g h = 0 + 2 * 9.8 * 50 = 980

When the stone is penetrating the sand:

v² = u² + 2 a s

0 = 980 + 2 * a * 1

a = - 490 m/s²

Average resistance Force offered by sand = m a = - 5 * 490

=- 2, 450 N

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