章节大纲

  • A brightly colored hot air balloon flying over a landscape with a mountain and village.

    How are hot air balloons able to move smoothly in the air?
    ::热气球如何能在空气中顺利移动?

    Many people enjoy riding in hot air balloons. Some use them for romantic picnics and marriage proposals. Others race in competitions. Being above the earth gives a whole new perspective on the world around us. As the beginning of a hot air balloon ride, the balloon is flat because the pressure inside the balloon equals the pressure outside. When the air inside the balloon is heated, the speed of movement of those air molecules increases and the pressure goes up. After a while the balloon is completely expanded and the flight is ready to take off.
    ::许多人喜欢坐热气球。 有些人用热气球来进行浪漫的野餐和婚姻求婚。 另一些人则在竞赛中竞争。 地球上空给我们周围的世界带来了全新的视角。 随着热气球飞行的开始,气球是平的, 因为气球内的压力等于外面的压力。 当气球内的空气被加热时, 这些空气分子的移动速度会加快,压力也会上升。 在气球完全膨胀,飞行准备起飞之后,气球的移动速度会加快。

    Gas Pressure
    ::气气压力

    Pressure is defined as the force per unit area on a surface.
    ::压力定义为表面每单位面积的功率。

    Pressure = force area

    ::压力=军力面积

    When a person stands on the floor, his feet exert pressure on the surface. That pressure is related to both the mass of the person and the surface area of his feet. If the person were holding a heavy object, the pressure would increase because of a greater force. Alternatively, if the person stands on his toes, the pressure also increases because of a decrease in the surface area.
    ::当一个人站在地上时,他的脚对地表施压,这种压力与人的重量和脚的表面面积有关,如果该人持有重物,压力会因更大的力而增加,或者,如果该人站在脚趾上,压力也会因表面面积减少而增加。

    molecules also exert pressure. Earth’s atmosphere exerts pressure because gravity acts on the huge number of gas particles contained in the atmosphere, holding it in place. Pressure is also exerted by a small sample of gas, such as that which is contained in a balloon. Gas pressure is the pressure that results from collisions of gas particles with an object. Inside the balloon, the gas particles collide with the balloon’s inner walls. It is those collisions which keep the balloon inflated. If the gas particles were to suddenly stop moving, the balloon would instantly deflate. Figure is an illustration of gas particles exerting pressure inside a container.
    ::气压是气体粒子与一个物体碰撞所产生的压力。气压在气球内与气球内壁相撞。正是这些碰撞使气球膨胀。如果气体粒子突然停止移动,气球会立即变形。 数字是气体粒子在容器内施压的例子。

    Gas particles colliding with container walls, demonstrating gas pressure dynamics.

    Collision of gas particles with container wall.
    ::气体粒子与集装箱墙相撞。

    The pressure inside the hot air balloon is affected by temperature . As the molecules up, they move faster and strike the inside wall of the balloon harder. This increased motion of the gas particles increases the force on an area of the balloon, producing a rise in the pressure.
    ::热气球内部的压力受到温度的影响。 当分子上升时, 它们移动得更快, 更用力地撞击气球内部的墙壁。 气体粒子增加的动作会增加气球一个区域的力量, 导致压力上升 。

     

     

    Summary
    ::摘要

    • Pressure is defined as force area .
      ::压力定义为压力区域。
    • Gas pressure is the result of collisions between gas particles and an object.
      ::气体压力是气体粒子与物体碰撞的结果。
    • An increase in temperature will produce an increase in pressure of a gas.
      ::温度升高将导致气体的压力增加。

    Review
    ::回顾

    1. What is pressure?
      ::什么是压力?
    2. How does a gas create pressure on an object or container?
      ::气体如何对物体或容器造成压力?
    3. What would happen to the pressure if gas particles suddenly stopped moving?
      ::如果气体粒子突然停止移动 压力会怎样?
    4. How does temperature affect pressure?
      ::温度如何影响压力?