ρ水=1 g / ml
因为
m水=m瓶水-m瓶=100 g - 20 g = 80 g
m液=m瓶液-m瓶=120 g - 20 g = 100 g
V = m / ρ水 = 80 / 1 = 80ml
所以
ρ液 = m液/V = 100 g / 80ml = 1.25 g / ml
ρ水=1 g / ml
因为
m水=m瓶水-m瓶=100 g - 20 g = 80 g
m液=m瓶液-m瓶=120 g - 20 g = 100 g
V = m / ρ水 = 80 / 1 = 80ml
所以
ρ液 = m液/V = 100 g / 80ml = 1.25 g / ml