10.5 摩擦类型
Section outline
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Climbing a vertical rock wall means pitting your strength and stamina against the force of gravity, which pulls you down toward the ground. Another force helps you to climb the vertical rock wall by keeping your hands and feet from slipping. That force is .
::爬上垂直的岩石墙意味着将你的力力和毅力与引力相抵,引力将你拉向地面。另一股力有助于你通过保持你的手和脚不滑落而爬上垂直的岩石墙。那股力就是 。Four Types of Friction
::四类摩擦Friction is the force that opposes motion between any surfaces that are in contact. There are four types of friction: static, sliding, rolling, and fluid friction. Static, sliding, and rolling friction occur between surfaces. Fluid friction occurs in and . All four types of friction are described below.
::摩擦是反对接触中的任何表面之间运动的力量。 摩擦有四种类型: 静态摩擦、 滑动摩擦、 滚动摩擦和流体摩擦。 静态摩擦、 滑动摩擦和滚动摩擦在表面之间发生。 流动摩擦在其中发生。 所有四种摩擦都描述如下 。Static Friction
::静电摩擦Static friction acts on objects when they are resting on a surface. For example, if you are hiking in the woods, there is static friction between your shoes and the trail each time you put down your foot (see Figure ). Without this static friction, your feet would slip out from under you, making it difficult to walk. In fact, that's exactly what happens if you try to walk on ice. That's because ice is very slippery and offers very little friction.
::静态摩擦作用于在表面休息的物体。例如,如果你在树林里徒步旅行,你的鞋子和脚下脚下的足迹之间就会发生静态摩擦(见图 ) 。没有这种静态摩擦,你的脚就会从你的脚下滑出来,使其难以行走。事实上,这就是你试图在冰上行走时会发生的情况。这是因为冰非常滑,几乎没有什么摩擦。Q : Can you think of other examples of static friction?
::问:你能想到静态摩擦的其他例子吗?A : One example is the friction that helps the people climb the rock wall in the opening picture above. Static friction keeps their hands and feet from slipping.
::举例来说,摩擦帮助人们爬上上文的开场白中的岩石墙。 静态摩擦使他们的手脚不会滑倒。Sliding Friction
::滑滑摩擦Sliding friction is friction that acts on objects when they are sliding over a surface. Sliding friction is weaker than static friction. That's why it's easier to slide a piece of furniture over the floor after you start it moving than it is to get it moving in the first place. Sliding friction can be useful. For example, you use sliding friction when you write with a pencil. The pencil “lead” slides easily over the paper, but there's just enough friction between the pencil and paper to leave a mark.
::滑动摩擦是摩擦, 当物体滑过表面时, 滑动摩擦作用在物体上。 滑动摩擦比静态摩擦弱。 这就是为什么在开始移动之后, 将一块家具滑到地板上比让它移动更容易。 滑动摩擦可能有用。 例如, 用铅笔写作时使用滑动摩擦。 铅笔“ 铅笔” 幻灯片很容易在纸上贴上, 但是铅笔和纸纸之间只有足够的摩擦才能留下标记 。Q : How does sliding friction help you ride a bike?
::问题:滑动摩擦如何帮助你骑自行车?A : There is sliding friction between the brake pads and bike rims each time you use your bike's brakes. This friction slows the rolling wheels so you can stop.
::A: 刹车垫和自行车轮圈之间有滑动摩擦,每次你用自行车刹车。这种摩擦会减慢滚轮速度,以便你停下来。Rolling Friction
::滚动摩擦Rolling friction is friction that acts on objects when they are rolling over a surface. For example, as a soccer ball rolls along the ground, it will come to a stop because the rolling friction acts in the opposite direction to the motion of the ball. Rolling friction is much weaker than sliding friction or static friction. This explains why most forms of ground transportation use wheels, including bicycles, cars, 4-wheelers, roller skates, scooters, and skateboards. Ball bearings are another use of rolling friction. You can see what they look like in the Figure . They let parts of a wheel or other roll rather than slide over on another.
::滚动摩擦是摩擦,当物体在表面滚动时对物体起作用。例如,作为足球球滚动在地面上,它会停止,因为滚动摩擦与球动向相反。滚动摩擦比滑动摩擦或静态摩擦弱得多。这解释了为什么大多数地面运输形式都使用轮子,包括自行车、汽车、四轮车、滚滑冰鞋、滑板和滑板。球轴承是滚动摩擦的另一种用途。你可以看到图中它们的样子。它们让一个方向盘或其他滚动的部件而不是滑到另一个方向盘上。The ball bearings in this wheel reduce friction between the inner and outer cylinders when they turn. Fluid Friction
::流流摩擦Fluid friction is friction that acts on objects that are moving through a fluid. A fluid is a substance that can flow and take the shape of its container. Fluids include liquids and gases. If you've ever tried to push your open hand through the water in a tub or pool, then you've experienced fluid friction. You can feel the of the water against your hand. Look at the skydiver in the Figure . He's falling toward Earth with a parachute. Resistance of the air against the parachute slows his descent. The faster or larger a moving object is, the greater is the fluid friction resisting its motion. That's why there is greater air resistance against the parachute than the skydiver's body.
::流体摩擦是一种摩擦,它作用于正在流体中移动的物体上。流体是一种可以流动的物质,可以以其容器的形式形成。流体包括液体和气体。流体包括液体和气体。如果你曾经试图在浴缸或游泳池中将开放的手从水中推过水,那么你就会经历流体摩擦。你可以感觉到水对你的手的摩擦。看看图中的天空分流器。他正在用降落伞向地球倾斜。空气对降落伞的抵抗会减缓他的下降速度。移动的物体越快越大,抵抗运动的液体摩擦就越大。这就是为什么对降落伞的空气抵抗力要大于天空分流体。Watch the video below to learn more about the different types of friction:
::观察下面的影片, 以了解更多不同摩擦类型:Summary
::摘要-
Friction is the force that opposes motion between any surfaces that are in contact. There are four types of friction: static, sliding, rolling, and fluid friction.
::摩擦是反对任何接触表面之间运动的力量。 摩擦有四种类型:静态摩擦、滑动摩擦、滚动摩擦和流体摩擦。 -
Static, sliding, and rolling friction occur between solid surfaces. Static friction is strongest, followed by sliding friction, and then rolling friction, which is weakest.
::固态表面之间会出现静态、滑动和滚动摩擦。 静态摩擦最强,其次是滑动摩擦,其次是最弱的滚动摩擦。 -
Fluid friction occurs in fluids, which are liquids or gases.
::流体摩擦发生在液体或气体的液体中。
Review
::回顾-
List four types of friction.
::列出四种摩擦类型。 -
You can move heavy boxes by sliding them over the ground. Or you can put them on a dolly, like the one in the
Figure
, and then roll them over the ground. Explain which way makes it easier to move the boxes.
::你可以把它们滑到地上移动重箱。 或者你可以把它们放在一个圆圈上, 就像图中的那个一样, 然后把它们滚到地上。 解释一下哪个方法可以更容易移动盒子 。 -
What is a fluid? Give an original example of fluid friction.
::流体摩擦的原创例子
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Friction is the force that opposes motion between any surfaces that are in contact. There are four types of friction: static, sliding, rolling, and fluid friction.
