Question

A monkey sitting in tree at a height of 19.6m, drop a 10g seed of rose apple on a crocodile, at rest below the tree. If the seed falls in the mouth of the crocodile in 2s time and becomes stationary, then the momentum gained by the crocodile(in addition to the seed) is _____kg m/s. ( g=9.8 m/s^2)

Answer 1

Let v is the speed of seed when it falls in the mouth of the crocodile.

using formula, v² = u² + 2as

given, S = 19.6 m and t = 2sec , u = 0

or, v² = 0² + 2(-9.8)(-19.6)

or, v = 19.6 m/s

there is no external force acts on system of crocodile and seed.

so, linear momentum of system of crocodile and seed remain constant.

momentum lost by seed = momentum gained by crocodile

or, mass of seed × velocity of seed = momentum gained by crocodile.

or, 10g × 19.6 m/s = momentum gained by crocodile

or, momentum gained by crocodile = 196 × 10^-3 Kg m/s = 0.196 Kgm/s