Question

A 6kg fish swims toward and swallows a 2kg fish that is swimming towards the fish at a velocity of -2m/s. If the larger fish swims at 1m/s, what is its velocity after eating its lunch?

a) 1.2 m/s
b) 1.4 m/s
c) 1.6 m/s
d) 1.8 m/s

Answer 1

The velocity of the larger fish after eating the smaller fish is 0.5 m/s.

Step-by-step explanation:

To calculate the velocity of the larger fish after eating the smaller fish, we can use the law of conservation of momentum. The initial momentum of the small fish can be calculated as the product of its mass (2 kg) and its velocity (-2 m/s), which is -4 kg*m/s. Since the larger fish is at rest initially, its momentum is 0 kg*m/s.

After eating the small fish, the larger fish's mass becomes 6 kg + 2 kg = 8 kg. Using the equation p = mv, where p is momentum, m is mass, and v is velocity, we can solve for the velocity:

0 kg*m/s + (-4 kg*m/s) = 8 kg * v

Therefore, the velocity of the larger fish after eating its lunch is -0.5 m/s. Since velocity is a scalar quantity and the question asks for the magnitude, the answer is 0.5 m/s.