Question

Two ice skaters stand in the middle of an ice rink. Drew has a mass of 75 kg, and Lily has a mass of 55 kg. Drew holds Lily, and they are both stationary. To begin their routine, he tosses her forward with a speed of 2 m/s.
a. The system is defined as Drew and Lily. What is the total momentum of the system before he throws her?

b. What is the total momentum of the system after he throws her?

c. What is the velocity of Drew after he throws her?

Answer 1

PART a)

Before Drew throw Lily in forwards direction they both stays at rest

So initial speed of both of them is zero

So here we can say that initial momentum of both of them is zero

So total momentum of the system initially = ZERO

PART b)

Since there is no external force on the system of two

so there will be no change in the momentum of this system and it will remain same as initial momentum

So final momentum of both of them will be ZERO

PART c)

As we know that momentum of both will be zero always

so we have

$P_1 + P_2 = 0$

$75(v) + 55(2) = 0$

$v = 1.47 m/s$ in opposite direction

Answer 2

a) p=0 since everybody's stationary

b) 0 according to law of conservation of momentum

c) 74u-55*2=0, solve,

u=1.47 m/s