Posted by phillip on .
john and Sarah participated in a roller skating show. while 75kg john skated backwards at 3.00m/s, 60kg Sarah jumped into his arms with a velocity of 5m/s in the same direction.
a. how fast did the pair roll backwards together?
b. if john instead skated toward sissy when she jumped, would their combined final velocity have been larger or smaller than the answer in a.
i trying to figure out how to set this equation up thankyou very much if you help me

Physics 
drwls,
Kinetic energy is lost in both processes, but momentum is conserved. The momentum conservation equation becomes:
a. 75*3.0 + 60*5.0 = (135)*Vfinal
b. 75*3.0 +60*5.0 = (135)*Vfinal
Compute and compare Vfinal values.