I'm having some trouble with this problem. I know the formulas, but I'm not sure how to insert them into this equation. Can I please have some help? I am looking for an explanation, not just an answer.

A boy and the skateboard on which he is standing have a combined mass of 60 kg. He throws a 1kg rock forward at 20 m/sec. At what speed will the boy roll backward?

I know that Speed = Distance/Time but I'm kind of having trouble because mass is in the problem but not in the equation.

Question

I'm having some trouble with this problem. I know the formulas, but I'm not sure how to insert them into this equation. Can I please have some help? I am looking for an explanation, not just an answer.

A boy and the skateboard on which he is standing have a combined mass of 60 kg. He throws a 1kg rock forward at 20 m/sec. At what speed will the boy roll backward?

I know that Speed = Distance/Time but I'm kind of having trouble because mass is in the problem but not in the equation.

osprey · Answer

This q is actually about CONSERVATION OF LINEAR MOMENTUM I think. combined mass times speed BEFORE throwing = mass times speed after throwing. of each mass added together separately. http://perendis.webs.com