(单词翻译:单击)
A simple machine is exactly what it sounds like: one of the "simplest" possible tools that can be used to increase force.
一台简单的机器就是听起来那样：一种可以增加力量的最“简单”的工具。
There are six basic types of simple machines, starting with the inclined plane.
简单的机器有六种基本类型，首先，来说说斜面。
An inclined plane can be pretty much any object--a ramp, a slide, or even just a block of wood--as long as it consists of a sloping surface.
斜面几乎可以是任何物体--坡道、滑梯，甚至只是一块木头--只要它是由一个倾斜的表面组成的。
Helpful when you're trying to lift heavy objects, the inclined plane offers a mechanical advantage: the force required to move an object up the incline is less than the weight being lifted.
想要举起重物时，斜面很有用，它能提供机械优势：将物体沿斜坡向上移动所需的力小于直接举起物体的重量。
The steeper the plane's incline, the closer the necessary force gets to the object's actual weight.
平面倾斜得越陡，所需的力就越接近物体的实际重量。
The lever is a bar or board that rests on a tipping point called a fulcrum.
杠杆是指位于被叫作支点的转折点上的杆或板。
Teeter-totters, salad tongs, and bottle openers are all levers, meaning that a downward force exerted on one end can be transferred and increased in an upward direction at the other end, allowing a small force to lift a heavy weight.
跷跷板、沙拉钳和开瓶器都是杠杆，这意味着在一端施加的向下的力，会在另一端向上传递并且增加，从而可以用小小的力量举起重物。
The wedge is a simple machine that's been used since prehistoric times.
楔子是一种简单的机器，史前时代就出现了。
It's any object tapered to a thin edge, like an ax or the teeth on a saw.
它是指带有锋利边缘的物体，比如斧头或锯子上的锯齿。
Pushing a wedge in one direction creates a force in a sideways direction.
往一个方向上推动楔子会产生横向的力。
The wheel and axle is made up of a circular frame that revolves around a shaft or rod--a device that, in its earliest forms, was probably used for lifting water buckets from wells.
轮轴是由一个围绕轴或杆旋转的圆形框架组成的--最早的时候，这种装置很可能是用来提水井里的水桶的。
When force is exerted on either the wheel or the axel, the other part moves as well.
如果给轮子或轴施加压力，另一部分也会移动。
The pulley is a wheel that carries a flexible rope, cord, cable, chain, or belt on its rim that's used to transmit energy and motion.
滑轮是指轮子，它的轮缘上装有柔性的绳子、绳索、缆索、链条或皮带，用来传递能量和运动。
Like inclined planes, pulleys are used to gain a mechanical advantage: objects are easier to lift using a pulley system than by using your own two hands.
与斜面一样，使用滑轮是为了获得机械优势：使用滑轮系统比用自己的双手更容易举起物体。
Lastly, the screw is typically a circular, cylindrical shaft that looks like, well... a screw.
最后，螺丝通常是指圆柱形的轴，看起来就像...螺丝。
Used as a fastener or as a force modifier, the screw is kind of like a wedge wrapped around a cylinder.
螺丝通常被用来当紧固件或力调节器，有点像缠绕在圆柱体上的楔子。
But the important part here is the threads.
但螺丝上的纹路很重要。
The closer together the threads are, the greater the mechanical advantage--thus making it easier to drive the screw into the object of your choosing.
螺纹距离越近，机械优势就越大--这样就更容易将螺钉拧入其他物体中。
