6.5 m/s is the velocity of the boy when a 65.0-kg boy and 40.0-kg girl, both wearing skates, face each other at rest on a skating rink.
Mass of the boy, = 65kg
girl's mass given , = 40 kg
Final velocity of the girl , = -4.00 m/s
By law of conservation of momentum
[tex]m_bv_ib+m_gv_ig=m_bv_fb+m_gv_fg[/tex]
[tex]0=65kg(-4.0m/s)+40kgv_fg[/tex]
[tex]v_fg=6.5m/s[/tex]
When a body is travelling in a straight line, its velocity is the "rate of change of displacement with relation to time."Because it always has a direction, velocity is a vector. As a result, when the displacement to time ratio for linear velocity is determined, it provides both the direction and the magnitude.
To know more about velocity visit : https://brainly.com/question/19979064
#SPJ4