Chapter 8219P8.2(a)We take the zero configuration of systempotential energy with the child at thelowest point of the arc. When the stringis held horizontal initially, the initialposition is 2.00 m above the zero level.Thus,Umgyg===4002 00800N mJafaf..(b)From the sketch, we see that at an angleof 30.0° the child is at a vertical height of2001300.cos.mafaf−°above the lowestpoint of the arc. Thus,FIG. P8.2gyg−°=4002 00130 0107mJafafafos..(c)The zero level has been selected at the lowest point of the arc. Therefore, Ug=0 at thislocation.*P8.3The volume flow rate is the volume of water going over the falls each second:305 1218m mmsms3.bg=The mass flow rate is mtVt=ρ1 0001 81 800kg mm skg s33ejej.If the stream has uniform width and depth, the speed of the water below the falls is the same as thespeed above the falls. Then no kinetic energy, but only gravitational energy is available forconversion into internal and electric energy.The input power is Pin2energykg sm smJ s===×tmgytmtgy1 8009 858 82 104The output power is
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .