# Conservation of energy problem on an igloo

1. Nov 10, 2009

### ap.p.b.studen

1. The problem statement, all variables and given/known data
Jin is sitting on top of a hemispherical, frictionless igloo of radius 2.40 meters. His friend pushes him, giving him an initial speed. Jin slides along the igloo and loses contact with it after he has traveled 1.60 meters along the surface. What was his initial speed?

2. Relevant equations
KEi+PEi=KEf+PEf

Ei=Ef

F=macos(angle)

Work=KE+PE

Work=Fx(delta x)

PE=mgh

KE=.5(m)(v^2)

3. The attempt at a solution

I drew a picture of a semicircle and used the S=theta(r) equationand trignometry to find that the hieghts (2.40m initial and 1.89m when leaves igloo). I used the conservation of energy to find that the velocity when Jin leaves the igloo is 3.16m/s. How would I find the initial velocity?

2. Nov 10, 2009

### paul232

How did you find 3.16? Kinetic in the initial condition is not zero.. You are trying to find the velocity.. How could it be zero?

Also think about what happens at the exact moment it leaves the semicircle and what kind of motion it executes.. You didnt write one equation you need.

Hope it helps