A two-stage rocket is traveling at 1210m/s with respect to the earth when the first stage runs out of fuel. Explosive bolts release the first stage and push it backward with a speed of 40m/s relative to the second stage after the explosion. The first stage is three times as massive as the second stage. What is the speed of the second stage after the separation? (m/s)

the overall velocity of the second stage after separation is = 1240 m/s.

Explanation:

We are told that the first stage is three times as massive as the second stage.

Now, If the second stage has mass M, the total mass of the first and second stages = M + 3M = 4M.

Now, since the stages are separating at 40 m/s, the lighter second stage must have received most of that velocity change which by proportion is; (3/4) x 40 = 30 m/s

Thus, stage two has added 30 m/s to its velocity.

Thus, the overall velocity of the second stage after separation is now;

1210 + 30 m/s = 1240 m/s.

there are no contact forces mentioned on the list of choices that you've provided.