What Is the Mass of the Second Ice Skater?

[eagles12]

Homework Statement

Two ice skaters stand at rest in the center of an ice rink. When they push off one another, the 60 kg skater acquires a speed of .61 m/s. If the speed of the other skater is .8m/s what is this skater's mass?

Homework Equations

explosion- pi=pf

The Attempt at a Solution

1/2m1v1^2=m2v2^2
1/2(60)(.61^2)=m2(.8^2)
11.16=m2(.64)
m2=17.43 but it said this was wrong

but then i got a really big number which doesn't seem right

 

[gneill]

Recheck your formulas. What's the formula for the momentum of a moving body?

 

[eagles12]

p=mv?

 

[gneill]

p=mv?

Is that a guess?

 

[eagles12]

so do i do m1v1=m2v2 instead of squaring the velocities

 

[eagles12]

got it! thanks

 

[BruceW]

yes, that's right man. Its simply conservation of momentum.

 

[HallsofIvy]

There is NO "conservation of energy" (which is what you were trying to use first) because the "explosion" (push) adds energy to the system.