70 Racecars-Mid

Racecars FOCUS Question How do the parts of a racecar affect how it moves?

赛车焦点问题赛车的部件如何影响它的运动?

Speed and Direction Zoom! The racecars seem to fly past. They are fast, colorful, and extremely loud! Racecars can be built to go long or short distances. They can be built for different kinds of races. What all racecars have in common is that they are built to go fast, Very, very fast! Racecars that are speeding down the track have a lot of kinetic energy—the energy of motion Speed is how fast something is moving. To describe the speed of something identify the distance it traveled and the time it took. If a racecar travels 56 meters in one second, its speed is 56 meters per second That is about 200 kilometers (125 mi.) per hour. Not all racetracks are straight. Some include turns. When a racecar slows down or turns a corner, its velocity changes. Velocity is the speed that the object travels, combined with the direction it travels.

速度和方向缩放!赛车似乎在飞驰而过。 他们速度快，色彩鲜艳，而且非常大声!赛车可以跑长距离或短距离。 它们可以为不同种类的种族建造。 所有的赛车都有一个共同点，那就是它们都是为了跑得快而造的，非常非常快!在赛道上加速的赛车有很大的动能——运动的能量。速度是物体运动的速度。 要描述某物的速度，请确定它行进的距离和所花费的时间。 如果一辆赛车一秒钟跑56米，它的速度是56米每秒，大约是每小时200公里(125英里)。 并非所有的赛道都是直的。 有些包括转弯。当赛车减速或转弯时，它的速度会发生变化。 速度是物体运动的速度，加上它运动的方向。

Kinetic Energy Think about walking around a track. You can measure your speed and velocity as you move. Now think about running on the track as fast as you can. Your speed increases, which means your velocity increases. The faster you run, the more kinetic energy your body has. The faster a racecar goes, the more kinetic energy it has, too. Kinetic energy also depends on the mass of the moving object. If two objects of the same mass are moving at different velocities, the faster one has more kinetic energy. But if two objects of different masses are moving at the same velocity, then the object with larger mass has more kinetic energy. No one would race a dump truck against a racecar. The dump truck needs so much energy to move fast that it cannot compete. Kinetic energy (KE) depends on mass (m) and velocity (v). KE = ½ mv2 Notice that velocity is squared (v2 means v times v) but mass is not. That means a change in velocity affects kinetic energy more than a change in mass will. If the dump truck and racecar are going the same speed. which has more kinetic energy?

想象一下在跑道上行走。 你可以测量你移动时的速度和速度。 现在想象一下在跑道上以最快的速度奔跑。 你的速度增加，这意味着你的速度增加。 你跑得越快，你身体的动能就越多。 赛车跑得越快，它的动能也就越大。 动能也取决于运动物体的质量。 如果两个质量相同的物体以不同的速度运动，速度快的物体有更多的动能。 但是如果两个不同质量的物体以相同的速度运动，那么质量大的物体就有更多的动能。 没人会让自卸卡车和赛车比赛。 自卸卡车需要如此多的能量才能快速移动，以至于它无法与之竞争。 动能(KE)取决于质量(m)和速度(v)。 注意，速度是平方(v2意味着v乘以v)，但质量不是。 这意味着速度的变化对动能的影响大于质量的变化。 如果自卸卡车和赛车的速度相同。 哪个的动能更大?

From Family Car to Racecar Stock cars, are similar to regular family cars but they are changed, or modified, so that they can go as fast as possible for their mass. In fact, all types of racecars have modifications that make them fast! Spoilers increase downforce. Downforce is a force that pushes the car down. It helps the car stay low to the ground when turning. When a car is aerodynamic. its body is designed to reduce air resistance. Air resistance is the force of the air pushing against an object as the object moves. It slows the car. The tires of a racecar are different than those of a family car. The grip, or traction, between the tires and ground help propel the car forward. Racecar tires are smoother than tires on a regular car to give the racecar better traction on the track.

从家用汽车到赛车库存汽车，与普通家用汽车类似，但它们经过了改变或改装，以便它们能以尽可能快的速度行驶。 事实上，所有类型的赛车都经过了改装，使它们变得更快!扰流器增加下压力。 下压力是一种将汽车向下推的力。 它可以帮助汽车在转弯时保持低地面。 当汽车是空气动力学的时候。 它的机身设计是为了减少空气阻力。 空气阻力是物体移动时空气对物体的推力。 它使汽车减速。赛车的轮胎和家用汽车的轮胎是不同的。 轮胎和地面之间的抓地力或牵引力有助于推动汽车前进。 赛车轮胎比普通汽车的轮胎更光滑，从而使赛车在赛道上有更好的牵引力。

The engine of a racecar is more powerful than that of a regular car. A stock car's engine can achieve more than 750 horsepower (HP). This is a measurement of how fast the engine can do work, or move the car. A regular car produces about 120 HP. Word Wise Before the invention of the steam engine, most energy for large machines came from horses. The power of the new engines was compared to the number of horses needed to provide the same power. The unit was called one horsepower.

赛车的发动机比普通汽车的发动机动力更大。 普通汽车的发动机可以达到750马力(HP)以上。 这是一个衡量发动机工作或移动汽车的速度的指标。 一辆普通汽车大约产生120马力。 在蒸汽机发明之前，大型机器的大部分能量来自于马。 新发动机的功率与提供相同功率所需的马匹数量进行了比较。 这个单位叫做一马力。

NASCAR Racing The National Association for Stock Car Auto Racing, or NASCAR, is an organization that oversees stock car races. Have you heard of the Daytona 500? It is a famous NASCAR race held in Daytona Beach, Florida. The race is 500 miles long! This means NASCAR vehicles must be designed to drive a long distance in addition to going fast. The racetrack in Daytona is 2.5 miles long and shaped like an oval. Drivers make 200 laps of the course (500 miles). In some years the winners have averaged more than 175 mph for the race, finishing in less than 3 hours of actual racing time.

全美汽车竞赛协会，简称NASCAR，是一个监督汽车竞赛的组织。 你听说过代托纳500吗? 这是在佛罗里达州代托纳海滩举行的著名的纳斯卡赛车比赛。 比赛有500英里长!这意味着纳斯卡赛车的设计除了速度快之外，还必须能行驶很长的距离。 代托纳的赛马场长2.5英里，形状像椭圆形。 车手要在赛道上跑200圈(500英里)。 在某些年份，获胜者的平均时速超过175英里，在实际比赛时间不到3小时内完成比赛。