ADDITIONAL INO ADDED AT BOTTOM
a spectator at a hockey game is sitting in a seat situated 10.4m above ground leve. if the spectator has a mass of 52.6 kg, calculate her gravitational potential energy relative to:
a)ground level
Eg=mgh
=52.6X9.8X10.4
=5360.99J
b)the ice surface
Eg=mgh
=52.6X9.8X13.2
=6804J
PHYSICS - please check my work - drwls, Sunday, January 31, 2010 at 10:12am
Part (a) is correct and the formula you use is correct, but you don't say what the ice surface elevation is. You do the problem as if the ice surface were 2.8 m below ground level.
SORRY - THE ICE SURFACE IS 2.8 M BELOW GROND LEVEL. SO I ADDED THE 2.8 AND THE 10.4 TOGETHER, IS THAT CORRECT? THANKYOU.
No. The PE relative to the surface below the ice will be
PE=mgh=52.5*g*(-2.8m)
notice the PE is negative, it takes energy to get the object back to the surface. PE is always relative to some arbitary reference point.