Calculating Take-Off Speed Using Newton's Third Law

[Bostonpancake0]

question is 29./ about bob and throwing his rock, I have found a./ (225N) easily enough it is b./ which i cannot figure out. I am assuming that it is a Newtonian action-reaction pair and that the rock pushes back on bob at 225N as well, which would mean Bob's acceleration would be 3.0ms/s^2. But how do i found his take off speed (I'm asuming kinematics but not sure how with missing variables)??


Answer is 0.2m/s which i can't understand??

 

[ap123]

Could you post the complete question.

 

[Bostonpancake0]

hahhaha didnt even post the question, there you go

 

[ap123]

The simplest way to do this is with conservation of momentum.

 

[Bostonpancake0]

thanks, didnt think of that