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    A cargo ship floating on water, demonstrating Archimedes' Law of buoyancy.

    This cargo ship displaces an amount of water such that the of the displaced water is exactly equal to the weight of the ship and its cargo. The displacement of water is what produces the to float this ship. When this photo was taken, the ship was empty so it did not sink very deep in the water to displace the necessary weight. When this ship is fully loaded with cargo, the water line will be where the black paint meets the red paint.
    ::这艘货轮取代了水量,使流离的水量与船舶及其货物的重量完全相等。水量的移位是该船浮出水面的产物。拍到这张照片时,该船是空的,因此没有沉入水深以取代必要的重量。当该船满载货物时,水线将是黑漆与红漆相匹配的地方。

    Archimedes’ Law and Buoyancy
    ::考古法和浮力

    If an object is submerged in a liquid, the object displaces a volume of the liquid equal to the volume of the submerged object. Legend has it that this observation was made by Archimedes when he sat in a bath tub that was filled to the top of the tub. The volume of water that overflowed was equal to his own volume. The forces exerted by the fluid on the sides of the submerged object are balanced. However, the forces exerted by the fluid on the top and bottom of the object are not equal. The force exerted by the liquid below the object is greater than the force exerted by the liquid above it; the liquid exerts a net upward force on the submerged or floating object. This force is called buoyancy , and its magnitude is equal to the weight of the displaced water.  Archimedes' law  states that the buoyant force is equal to the weight of the displaced liquid.
    ::如果一个物体被水浸在液体中,该物体将取出与水下物体体积相等的液体体积。传说显示,这种观察是由Archimedes在坐在浴缸顶部的浴缸里时进行的。溢出的水量相当于他自己的体积。水分在水下物体两侧的液体力是平衡的。但是,物体顶部和底部的液体力是不平等的。物体下方的液体力大于其上方液体力;液体在水下或漂浮物体上施以净向上力。这支力称为浮力,其体积相当于流水的重量。Archimedes的法律规定浮力等于流液体的重量。

    Examples
    ::实例

    Example 1  
    ::例1

    The density of steel is 9000. kg/m 3 and the density of water is 1000. kg/m 3 . If a cube of steel that is 0.100 m on each side is placed in a tank of water and weighed while under water, what is the apparent weight of the cube?
    ::钢的密度为9000公斤/立方米,水的密度为1000公斤/立方米。 如果每边0.100米的钢立方体放在水箱中,在水下称重,立方体的明显重量是多少?

    The volume of the cube is 0.00100 m 3 .
    ::立方体的体积是0.00100立方米。

    The mass of the cube is 9.00 kg.
    ::立方体的质量为9.00千克。

    The weight of the cube when not submerged in water = (9.00 kg)(9.80 m/s 2 ) = 88.2 N
    ::未浸入水中的立方体的重量=(9.00公斤)(9.80米/秒)=88.2牛顿。

    The mass of water displaced by the cube = 1.00 kg
    ::立方体流出的水质量=1.00千克

    The weight of the water displaced by the cube = 9.80 N
    ::立方体排出的水的重量=9.80牛顿

    The buoyant force on the steel cube = 9.80 N
    ::钢立方体上的浮力=9.80 N

    Apparent weight of cube under water = 88.2 N - 9.80 N = 78.4 N
    ::水下立方体表面重量=88.2 N - 9.80 N = 78.4 N

    Example 2  
    ::例2

    A hollow metal cube 1.00 m on each side has a mass of  600. kg.  How deep will this cube sink when placed in a vat of water?
    ::每边的空心金属立方体1.00米的重量为600公斤。如果将这个立方体放入水缸中,它会沉入多深?

    Since the weight of the cube is 5880 N, it will need to displace 5880 N of water in order to float.
    ::由于立方体的重量为5880牛顿,它需要取代5880牛顿的水才能漂浮。

    Volume of submerged portion of cube = ( 1.00   m ) ( 1.00   m ) ( x   m ) = x   m 3
    ::立方体 = (1.00 m) (1.00 m) (1.00 m) (x m) =x m3 的沉积部分

    Mass of water displaced = 1000 x   kg
    ::流水质量=1000x千克

    Weight of water displaced = 9800 x   N
    ::缺水量的重量=9800xN

    9800 x = 5880
    ::9800x=5880

    x = 0.600   m
    ::x=0.600米xx=0.600米

    The cube will sink such that 0.60 m are underwater and 0.40 m are above water.
    ::立方体将沉到水下0.60米,水下0.40米。

    Have you ever gone fishing? A sinker is often attached to a fishing line in order to sink the hook deep enough in the water to bait a fish. Use the simulation below to adjust the material of the sinker so that it submerges in the water. Then, play around with the different materials to see if they will sink or float. Challenge: Can you get the rubber ducky to sink?
    ::你曾经钓过鱼吗?一个沉船者往往被附在钓鱼线上,以便把钩子深沉到水中,诱鱼。用下面的模拟来调整沉船的材料,使其沉入水中。然后,与不同的材料一起玩耍,看它们会沉还是浮。挑战:你能让橡皮鸭沉下去吗?

     

     

    Further Reading
    ::继续阅读

    Summary
    ::摘要

    • If an object is submerged in a liquid, the object will displace a volume of the liquid equal to the volume of the submerged object.
      ::如果一个物体被液体淹没,该物体将取代与水下物体体积相等的液体体积。
    • The forces exerted by the fluid on the sides of the submerged object are balanced, but the forces exerted by the fluid on the top and bottom of the object are not equal.
      ::水下物体两侧的液体所施加的力量是平衡的,但物体顶部和底部的液体所施加的力量是不相等的。
    • The liquid exerts a net upward force on the submerged or floating object, called buoyancy.
      ::液体对水下物体或漂浮物体(称为浮力)产生净向上力。
    • The magnitude of buoyancy is equal to the weight of the displaced water.
      ::浮力的大小与流离失所的水的重量相等。
    • Archimedes' law states that the buoyant force is equal to the weight of the displaced liquid.
      ::Archimedes的法律规定,浮力相当于流体流失液体的重量。

    Review
    ::回顾

    1. A cylinder with a radius of 11 cm and a height of 3.4 cm has a mass of 10.0 kg.
      1. What is the weight of this cylinder?
        ::这个气瓶的重量是多少?
      2. What is the weight of this cylinder when it is submerged in water?
        ::当这个气瓶沉入水中时,它的重量是多少?

      ::圆柱体半径为11厘米,高度为3.4厘米,质量为10.0公斤。这个圆柱体的重量是多少?沉入水中时这个圆柱体的重量是多少?
    2. A wooden raft is 2.00 m wide, 3.00 m long, and 0.200 m deep.  The raft and its occupants have a mass of 700. kg.  How deep will the raft sink below the water when floating?
      ::木木筏宽2米,长3米,深0.200米。木筏及其占用者的质量为700公斤。木筏在漂浮时会沉到水下多深?
    3. For the raft in problem #2, how many 50. kg people can be added to the raft before it sinks completely under water?
      ::对于第2号问题中的木筏来说,在木筏完全沉入水下之前,有多少50公斤的人可以加入木筏?
    4. The density of gold is 19,320 kg/m 3 and the density of mercury is 13,500 kg/m 3 .  If a cube of gold that is 0.100 m on each side is placed in a tank of mercury and weighed while under the surface, what is the apparent weight of the cube?
      ::金的密度为19,320千克/立方米,汞的密度为13,500千克/立方米。 如果每边0.100米的金方块放在汞罐中,并在表面之下称重,立方体的明显重量是多少?