物理-浮力問題(40分)

MAN MAn Man man

2010-08-27 7:03 am

體積為20立方厘米的木塊浮在水面上,其水下部份為總體積的3/5,求木塊的重量和木塊的密度?
用物理代號(請在隔離以中文標明是甚麼~~
請列明公式和計算過程,thanks.

回答 (1)

天同

2010-08-27 5:34 pm

✔ 最佳答案

Volume of water displaced by the wood when it floats on water
= (3/5) x 20 cm^3 = 12 cm^3
hence, weight of water displaced = 12 x 1 gf = 12 gf (taking the density of water to be 1 g/cm^3)
By the Principle of Floatation, upthrust = weight of water displaced
thus, upthrust = 12 gf
Because upthrust = weight of wood
i.e. weight of wood = 12 gf = 0.012 kgf = 0.12 N (taking the acceleration due to gravity to be 10 m/s2)

Since mass of wood = 12 g,
density of wood = 12/20 g/cm^3 = 0.6 g/cm^3 = 600 kg/m^3

👍 0 👎 0