An 81 kg football player moving 6.5 m/s tackles and collides with a stationary 140 kg football player. What speed will the football players have in the moment after impact?

1 Answer
Nicolas
Oct 11, 2017

#4.9ms^-1#

Explanation:

  • First and foremost we measure #KE_1# (The kinetic energy of the individual tackling):

#KE = 1/2*m*v^2#

Where;

  1. #m# is the mass
  2. #v# is the speed/velocity

#:. KE_1 = 1/2 * 81 * (6.5)^2#

#rarr KE_1 = 1711.125#

Due to accuracy purposes, we shall take #1711.125# completely for #KE_1#

  • Now, according to the law of conservation of energy, #KE_1# will be equal to #KE_2#( the kinetic energy tranferred form the tackilng player to the colliding player)

#:.# #KE_2#=#1/2*m*v^2#

#rarr##1711.125=1/2*140*v^2#

And,

#(140v^2)/2#=#1711.125#

#140v^2#=#2(1711.125)#

#v^2=(2(1711.125))/140#

#v=sqrt((2(1711.125))/140)#

#rarr v =4.944ms^-1#

  • Therefore #v=4.9ms^-1#

I hope I was useful to solve your concern
; )

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