Physics MC

I don't have any idea to do it. PLEASE HELP ME!!!!!!!!


A rugby player, mass 120 kg, is running due south at 6.0 ms-1. He is tackled by an
opponent, mass 90 kg, running due east at 8.0 ms-1. Calculate the combined speed of
the joined players immediately after the tackle.

A 0 m s-1 E 4.8 m s-1
B 0.18 m s-1 F 9.2 m s-1
C 1.4 m s-1 G 14 m s-1
D 2.0 m s-1 H 38 m s-1

Maybe i can help you


Player A's (of mass 120 kg) momentum = 120 × 6 = 720 kg m/s to the south

Player B's (of mass 90 kg) momentum = 90 × 8 = 720 kg m/s to the east

Therefore total momentum is, by the Pythagoras theorem, equal to:

720√2 kg m/s in the direction of southeast.

Hence their combined speed is:

720√2/(120 + 90) = 4.8 m/s

Therefore ans = E