问题 实验题

在探究“液体压强跟哪些因素有关”的实验中,进行了如图所示的操作:

(1)甲、乙两图是探究液体压强与液体    的关系.

(2)要探究液体压强与盛液体的容器形状是否有关,应选择丙和丁两图进行对比,结论是:液体压强与盛液体的容器形状    (填“有关”或“无关”).

(3)要探究压强与液体密度的关系,应选用    两个图进行对比.

答案

(1)深度;(2)无关;(3)乙丙

题目分析:液体内部压强与液体的密度和液体的深度有关,在探究影响液体内部压强的因素时,需要用到控制变量法.

(1)甲乙两图中的液体密度相同,探头所在深度不同,所以探究了探究液体压强与液体深度的关系;

(2)丙和丁液体密度相同,探头在液体中的深度相同,容器形状不同,U型管中液面的高度差相同,说明液体压强与盛液体的容器形状无关;

(3)要探究压强与液体密度的关系,应使探头深度相同,液体密度不同,所以应选择乙丙两图.

点评:此题是探究“液体压强跟哪些因素有关”的实验,考查了控制变量法在实验中的应用,是一道基础性题目

选择题
单项选择题

What might driving on an automated highway be like The answer depends on what kind of system is ultimately adopted. Two distinct types are on the drawing board. The first is a special-purpose lane system, in which certain lanes are reserved for automated vehicles. The second is a mixed traffic system: fully automated vehicles would share the road with partially automated or manual driven cars. A special-purpose 1ane system would require more extensive physical modifications to existing highways, but it promises the greatest gains in freeway (高速公路) capacity.

Under either scheme, the driver would specify the desired destination, furnishing this information to a computer in the car at the beginning of the trip or perhaps just before reaching the automated highway. If a mixed traffic system way was in place, automated driving could begin whenever the driver was on suitably equipped roads. If special-purpose lanes were available, the car could enter them and join existing traffic in two different ways. One method would use a special onramp (入口引道). As the driver approached the point of entry for the highway, devices installed on the roadside would electronically check the vehicle to determine its destination and to ascertain that it had the proper automation equipment in good working order. Assuming it passed such tests, the driver would then be guided through a gate and toward an automated lane. In this case, the transition from manual to automated control would take place on the entrance ramp. An alternative technique could employ conventional lanes, which would be shared by automated and regular vehicles. The driver would steer onto the highway and move in normal fashion to a "transition" lane. The vehicle would then shift under computer control onto a lane reserved for automated traffic. [The limitation of these lanes to automated traffic would, presumably, be well respected, because all trespassers (非法进入者) could be swiftly identified by authorities. ]

Either approach to joining a lane of automated traffic would harmonize the movement of newly entering vehicles with those already traveling. Automatic control here should allow for smooth merging without the usual uncertainties and potential for accidents. And once a vehicle had settled into automated travel, the driver would be free to release the wheel, open the morning paper or just relax.

When driving in an automated lane, the driver ().

A. should harmonize with newly entering cars

B. doesn’t have to rely on his computer system

C. should watch out for potential accidents

D. doesn’t have to hold on to the steering wheel