Question

1.Two skaters, Evelyn and Lily, face each other on near frictionless ice. Evelyn has a mass of 57.4 kg, and Lily has a mass of 48.3 kg. Both are motionless until they push away with a force of 33 N. Then Evelyn has a velocity of 1.4 m/s. What is Lily's velocity

Answer 1

Answer:

-1.67 m/s

Explanation:

We can solve this problem by using the law of conservation of momentum: in fact, since the system is isolated (no external forces, since the ice is frictionless), the total momentum of Evelyin and Lily must be conserved.

The total momentum before is zero, since they are both at rest:

$p_i = 0$

The total momentum after is:

$p_f = mv+MV$

where

m = 48.3 kg is Lily's mass

M = 57.4 kg is Evelyin's mass

V = 1.4 m/s is Evelyn's velocity

v is the Lily's velocity

Since momentum is conserved,

$p_i=p_f$

And so

$0=mv+MV$

Solving for v, we find Lily's velocity:

$v=-\frac{MV}{m}=-\frac{(57.4)(1.4)}{48.3}=-1.67 m/s$

And the negative sign indicates that her direction is opposite to Evelyn's direction.