Question

1,3,4三题，求学霸

Answer 1

1. G=mg=10^6kgx10N/kg=10^7N

   F浮=G=10^7N

F浮=ρ水gv排

V排=10^7N/1000kg/m^3x10N/Kg=10^3m^3

3. ρ木=0.8x10^3kg/m^3<ρ水  漂浮

F浮=ρ水gv排=G

V排=1.2N/1.0x10^3kg/m^3x10N/kg=1.2X10^-4m^3

4.m=G/g=0.18kg=180g

ρ=m/v=180g/120cm^3=1.5g/cm^3>ρ水  下沉

F浮=ρ水gv=1000kg/m^3x10N/kgx120x10^-6m^3=1.2N

FN+F浮=G

FN=0.6N