Question

q

Answer 1

here we have to apply the total momentum conservation law

Answer 2

here is the situation described in your problem:

Answer 3

if, after collision the two carts are attached together, then we can write this equation:
\[\Large 2m{v_0} = \left( {m + 2m} \right)u\]
where u is the final velocity

Answer 4

and v_0=5 m/sec

Answer 5

so after a simplification, we get:
\[\Large u = \frac{2}{3}{v_0} = ...?\]

Answer 6

more explanation:
the total momentum of our system before collision is:
\[\Large 2m{v_0}\]
whereas the total momentum of our system, after collision is:
\[\Large \left( {m + 2m} \right)u\]
those momentum have to be equal each other