A5-kg fish swimming 1 m/s swallows an absent minded 1-kg fish swimming toward it at a speed that brings both fish to a halt immediately after lunch. show that the speed of the approaching smaller fish before lunch must have been 5 m/s.

Explanation:

If we call the big fish as 1 and the small one as 2 we write their initial linear momentum as:

While their final linear momentum will be (since both are together we call their final velocity v):

But their final velocity is 0, so , and since linear momentum must be conserved we have , which means:

We want the speed of the approaching smaller fish (), so:

And just substitute our values:

Where the minus sign indicates that the small fish goes in the opposite direction as the big fish.

the answer would be c

the answer would be a