Afullback with a mass of 100kg and a velocity of 3.5 m/s duewest collides head-on with a defensive back with a mass of 80 kgand a velocity of 6 m/s due east.
a.)what is the initial momentum of each player? b.)what is the total momentum of the system before thecollision? c.)if they stick together and external forces can be ignored, what direction will they be traveling immediately after theycollide?

Answer

given,

mass of full back, M = 100 Kg

velocity of full back  in east = 3.5 m/s

mass of the defensive back,m = 80 Kg

velocity of defensive back, due east = 6 m/s

a) initial momentum of each player

  for full back

   P₁ = M v  =  100 x 3.5 = 350 kg.m/s

 for defensive back

   P₂= m v = 80 x 6 = 480 kg.m/s

b) total momentum before collision

     P = P₁ + P₂

taking west direction as positive

     P = 350  + (- 480 )

     P = -130 kg.m/s

c) speed of the them when they stick together.

    using conservation of momentum

   initial momentum = final momentum

    -130 = (M + m ) V

    180 V = -130

    V = -0.722 m/s

velocity after the collision is equal to 0.722 m/s in direction of east.