How Fast Was Kevin Skating Before the Inelastic Collision?

[agadag]

Homework Statement

Kevin has a mass of 84.2 kg and is skating with in-line skates. He sees his 23.2-kg younger brother up ahead standing on the sidewalk, with his back turned. Coming up from behind, he grabs his brother and rolls off at a speed of 1.74m/s. Ignoring friction, find Kevin's speed just before he grabbed his brother.

Homework Equations

V= d/t ?
I have no idea how to solve this eqn!
The only eqn i have for perfectly inelastic collision involves center of mass.

PLEASE HELP!

 

[sylas]

Homework Statement

Kevin has a mass of 84.2 kg and is skating with in-line skates. He sees his 23.2-kg younger brother up ahead standing on the sidewalk, with his back turned. Coming up from behind, he grabs his brother and rolls off at a speed of 1.74m/s. Ignoring friction, find Kevin's speed just before he grabbed his brother.

Homework Equations

V= d/t ?
I have no idea how to solve this eqn!
The only eqn i have for perfectly inelastic collision involves center of mass.

PLEASE HELP!

In an inelastic collision, kinetic energy is lost, but momentum is still conserved. Use conservation of momentum.