(1)∵ρ=[m/V],
∴m=ρV=7.8×103kg/m3×1×10-4m3=0.78kg,
G=mg
=0.78kg×9.8N/kg=7.644N;
(2)∵铁块浸没水中,
∴V排=V铁=1×10-4m3,
∴F浮=ρ水gV排
=1.0×103kg/m3×9.8N/kg×1×10-4m3
=0.98N;
(3)由题知,铁块浸没在水中静止,
G=F浮+F示,
∴弹簧秤示数:
F示=G-F浮
=7.644N-0.98N=6.664N.
答:(1)铁块的重力为7.644N.
(2)铁块所受到的浮力为0.98N.
(3)弹簧秤的示数为6.664N.