Hi there im new to the forum and I have a HW assignment due at 1130 pm tonight, i know im procrastinating :\ but physics is my weak point. I can not figure this question out if my life depended on it. Here it is: Identical twins, each with mass 64.2 kg, are on ice skates and at rest on a frozen lake, which may be taken as frictionless. Twin A is carrying a backpack of mass 12.0 kg. She throws it horizontally at 3.50 m/s to Twin B. Neglecting any gravity effects, what are the subsequent speeds of Twin A and Twin B? . They have the same mass, i know the masses should cancel correct? And we have to use the conservation of momentum . But can someone help me out ?