31. a big 8 kg fish swimming at 3 m/s opens its mouth and swallows a small 2 kg fish swimming
away from it at 1 m/s. presume water resistance is negligible. show your calculations.
(a) what is the momentum of the two fish system after the smaller fish has been
swallowed?
(b) what is the speed of the two fish system after the smaller fish has been swallowed?
(hint: first figure the mass of the two fish system.)

(A) 26kgm/s (B) 2.6m/s

Explanation:

This problem is a good example of an inelastic collision, in which the elements that collide remain together after the collision, and althogh the kinetic energy is not conserved, the linear momentum does.

Thus:  (1)

Where is the mass and the velocity.

 (2)

Where is the initial momentum and the final momentum.

(A) Momentum of the two fish system after the smaller fish has been  swallowed

(3)

Where is the initial mass (mass of the big fish) and is the initial velocity of the big fish, is the initial mass of the small fish and is the initial velocity of the small fish.

(4)

By the conservation of linear momentum:

(5)

(B) Speed of the two fish system after the smaller fish has been swallowed

In this case we will focus on (after the "collision"):

(6)

Where is the velocity of the system of both fish.

Finding :

(7)

Solving (7) and remembering :

(8)

Finally:

For me a person with a phd and who knows what there talking about.i know the chances of a radiation leak is low but if it does the area within a 96.3 mile radius would be unusable because of contamination

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current