Question

A 5kg fish swimming at 1 m/s swallows a 1 kg fish at rest. What is the final momentum of the big fish with the small fish in its stomach?

Answer 1

Answer:

$p = 4.167kgm/s$

Explanation:

Given

Represent the Big fish with M and the small fish with m

$M = 5kg$

$U_M = 1m/s$

$m = 1kg$

$U_m = 0m/s$

Required

Determine the final momentum of the Big fish

First, we need to determine the final velocity of the big fish.

Because, the big fish swallowed the small one, they both move at the same speed.

Using conversation of momentum, we have:

$M*U_M + m * U_m = (M + m)V$

Where

$V = Final\ Velocity$

So, we have:

$5 * 1 + 1 * 0 = (5 + 1)V$

$5 + 0 = 6V$

$5 = 6V$

$V = \frac{5}{6}\ m/s$

The momentum (p) is calculated as thus:

$p = M * V$

$p = 5 * \frac{5}{6}$

$p = \frac{25}{6}$

$p = 4.167kgm/s$

Hence, the final momentum is approximately 4.167kgm/s