"BEFORE COLLISION"
m_r=3" kg The red ball's mass"
v_r=16" "m/s " The velocity of red ball before collision"
P_r=m_r*v_r=16*3=48 kg*m/s
P_r:"(The red ball's momentum before collision)"
m_b=8" kg The blue ball's mass"
v_r=0" "m/s " The velocity of blue ball before collision"
P_b=m_b*v_b=8*0=0
P_b=0
P=P_r+P_b=48+0=48 kg*m/s
P:"(The Total momentum before collision)"
"AFTER COLLISION"
P_r^'=3*v_r^'" The red ball's momentum after collision"
P_b^'=8*v_b^' " The blue ball's momentum after collision"
P_^'=P_r^'+P_b^'
P^'=3*v_r^'+8*v_b^'
P^':"The total momentum after collision"
P=P^'" The conservation of momentum"
48=3*v_r^'+8*v_b^' " equation 1"
v_r+v_r^'=v_b+v_b^'" equation 2"
16+v_r^'=0+v_b^'
v_b^'=16+v_r^'" plug in equation 1"
48=3*v_r^'+8*(16+v_r^')
48=3v_r^'+128+8v_r^'
11v_r^'=48-128
11 v_r^'=-80
v_r^'=-80/11
v_r^'=-7.27" "m/s" The red ball's velocity after collision"
"So;"
v_b^'=16+v_r^'
v_b^'=16-7.27
v_b^'=8.73" "m/s" The blue ball's velocity after collision"