34 Machines That Build

Machines That Build by Whit Fisher

怀特·费舍尔的《建造机器

Chapter 1 What Is Work? Do you know what work is? The word work means different things to different people. For some people, work means a job they go to every day. Others say that thinking is hard work. An athlete might say that exercising is work. What do you think work is? Scientists have their own meaning of work. They say work is done when a force changes the motion of an object. Pushing a box across the floor is work because a force is moving the box. When you push or pull an object and change its motion, you are doing work. What about pushing against a wall? If the wall does not move, no work has been done.

第一章什么是工作?你知道什么是工作吗? “工作”这个词对不同的人有不同的含义。 对一些人来说，工作意味着他们每天都要去做的工作。 另一些人说，思考是一项艰苦的工作。 运动员可能会说锻炼就是工作。 你认为工作是什么? 科学家有自己的工作意义。 他们说当一个力改变物体的运动时做功。 把盒子推过地板就是做功，因为有一个力在移动盒子。 当你推或拉一个物体并改变它的运动时，你在做功。 推墙怎么样? 如果墙不动，就说明没有做功。

Chapter 2 Machines Help Us Work Machines are tools that help us do work. Think of the kinds of machines you see at a building site. They do work because they lift, push, and pull other objects. To understand how these machines work, you first have to understand simple machines. The Lever Simple machines have few moving parts. An example of a simple machine is a lever. A lever is a bar that moves on a fixed point. The fixed point is called a fulcrum. A seesaw is a kind of lever. On a seesaw, it is easy to move the other person in the air. It would be hard to lift that person yourself. The seesaw is a simple machine that makes lifting someone easier. A seesaw helps you do work, even as you play!

机器帮助我们工作机器是帮助我们工作的工具。 想想你在建筑工地看到的各种机器。 它们之所以做功，是因为它们举起、推着、拉着其他物体。 要了解这些机器是如何工作的，你首先要了解简单的机器。 杠杆简单机器只有很少的活动部件。 杠杆就是一个简单机械的例子。 杠杆是在固定点上移动的杆。 这个固定点叫做支点。 跷跷板是一种杠杆。 在跷跷板上，很容易在空中移动另一个人。 你自己很难把那个人抬起来。 跷跷板是一种简单的机器，可以让人抬起来更容易。 跷跷板可以帮助你工作，甚至在你玩耍的时候!

It would take many people to do the work of one power shovel. The power shovel uses a lever to help it lift heavy things. A big scoop is on the end of the lever. When the lever is lowered, the scoop fills with soil. When the lever is raised, it moves up the way a seesaw does. Yet the power shovel lifts soil instead of people. Then the power shovel can turn and drop the soil into a dump truck. The dump truck works like a lever, too. The back of the truck moves on a fixed point, so it is easy to dump the soil. Can you see the lever? By using a lever, the truck can move the soil easily.

一把电动铲的工作需要很多人来做。 电动铲使用杠杆来帮助它抬起重物。 杠杆的一端有一个大勺子。 杠杆一放下，铲子里就装满了土。 当杠杆被举起时，它就像跷跷板一样向上移动。 然而，电动铲铲起的是泥土，而不是人。 然后，电动铲可以转动，把土扔进自卸卡车。 自卸卡车也像杠杆一样工作。 卡车的后部在一个固定点上移动，所以倒土很容易。 你能看到杠杆吗?通过使用杠杆，卡车可以很容易地移动土壤。

Cranes are one of the oldest kinds of machines used for building. Some cranes use a lever to help lift heavy beams high into the air. These levers make it easier for the crane to lift and hold up a heavy weight. The Inclined Plane Another kind of simple machine is an inclined plane. An inclined plane is a flat surface that is raised at one end. A ramp is an inclined plane. This simple machine makes it easier to move things up and down. It helps people in wheelchairs go to different floors of a building without using stairs.

起重机是最古老的建筑机械之一。 有些起重机用杠杆帮助把沉重的横梁抬到空中。 这些杠杆使起重机更容易举起和支撑重物。 另一种简单的机器是斜面机。 斜面是一端凸起的平面。 坡道是一个斜面。 这台简单的机器使上下移动东西更容易。 它帮助坐轮椅的人不用楼梯就能到达大楼的不同楼层。