Physics help please?

Question

a 105 kg football player running due north at a speed of 9.5 m/s is tackled by an 80 kg player running in a direction 150 degrees east of north at a speed of 9 m/s. The collision occurs on wet Astroturf (astro-glass)so you can ignore friction.

a.) In what direction do the entangles players move after the collision?

b.) At what speed do they move after the collision?

Please give explainations for your answers. Thanks.

Answer 1

Momentum must be conserved

Vx1m1 + Vx2m2= Vx(m1+m2)
Vy1m1 + Vy2m2= Vy(m1+m2)
since Vx1=0

Vx2m2= Vx(m1+m2)
Vx=Vx2m2/(m1+m2)
Vx= V2cos(150)m2/(m1+m2)
Vx=9 cos(150)/(105 + 80)=
Vx= -0.041m/s

Vy1m1 + Vy2m2= Vy(m1+m2) then
Vy=[Vy1m1 + Vy2m2]/(m1+m2)
Vy=[9.5 sin(90) x105 + 9 sin(150) x 80]/(105 +80)
Vy= 7.34m/s

V= sqrt(Vx^2 + Vy^2)=7.34 m/s
angle A= 90+arctan(Vy/Vx)=
A=90+arctan(7.34/.041)= 90 + 0.32= 90.32 degrees
So they move 90.32 degrees east of north at the speed of 7.34 m/s.