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相关概念视频

Friction: Problem Solving01:17

Friction: Problem Solving

Friction is an essential force that influences the motion of objects in daily life. Depending on the situation, it can be either beneficial or problematic. Consider a bus with a mass of three megagrams and its center of mass at a specific point, moving along a banked road at a constant speed. The coefficient of static friction between the tires and the road is 0.5. Find the maximum angle of the banked road at which the bus would not slip or tip.
Initially, a visual representation of the...
Rolling Resistance01:21

Rolling Resistance

When a solid cylinder rolls steadily on a rigid surface, the normal force applied by the surface on the cylinder is perpendicular to the tangent at the contact point. However, since no materials are entirely rigid, the surface's reaction to the cylinder involves a range of normal pressures.
For instance, imagine a hard cylinder rolling on a comparatively soft surface. The cylinder's weight compresses the surface beneath it. As the cylinder moves, the material in front of it slows down due to...
Rolling Resistance: Problem Solving01:17

Rolling Resistance: Problem Solving

Rolling resistance, also known as rolling friction, is the force that resists the motion of a rolling object, such as a wheel, tire, or ball, when it moves over a surface. It is caused by the deformation of the object and the surface in contact with each other, as well as other factors like internal friction, hysteresis, and energy losses within the materials. Rolling resistance opposes the object's motion, requiring additional energy to overcome it and maintain movement. In practical...
Rolling Without Slipping01:09

Rolling Without Slipping

People have observed the rolling motion without slipping ever since the invention of the wheel. For example, one can look at the interaction between a car's tires and the surface of the road. If the driver presses the accelerator to the floor so that the tires spin without the car moving forward, there must be kinetic friction between the wheels and the road's surface. If the driver slowly presses the accelerator, causing the car to move forward, the tires roll without slipping. It is essential...
Rolling With Slipping01:14

Rolling With Slipping

Rolling with slipping is a physical phenomenon that occurs when a rolling object experiences both rotational and linear motion but also experiences frictional forces that cause slipping. This phenomenon can occur in various situations, such as when a tire rolls on a wet road or a ball rolls on a rough surface.
An object's rolling motion is characterized by its rotation around its axis, while linear motion refers to the object's translational motion along a surface. Frictional forces can affect...
Design Example: Designing Water Slide01:18

Design Example: Designing Water Slide

When designing a water slide, controlling the speed of water flow is crucial for rider safety while maintaining an exciting experience. As water flows down the slide, gravity causes it to accelerate, with its speed at the bottom depending on the height from which it starts. The higher the slide, the more potential energy the water has at the top, which is converted into kinetic energy as it descends, increasing its speed.
Bernoulli's principle determines the water's velocity along the slide.

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相关实验视频

Updated: Jul 7, 2026

Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling
06:55

Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling

Published on: August 5, 2016

荷兰科学:在平的滑坡上?

M Enserink

    Science (New York, N.Y.)
    |September 6, 2007
    PubMed
    概括

    荷兰科学在认可方面表现出色,但面临着挑战. 投资下降,科学职业减少和女性参与率低可能很快导致研究人员短缺.

    科学领域:

    • 荷兰的科学成果和全球地位.
    • 分析科学研究和开发的趋势.

    背景情况:

    • 荷兰科学通过诺贝尔奖和引用获得了高度的国际认可.
    • 人们担心荷兰的科学竞争力可能下降.

    研究的目的:

    • 评估荷兰科学研究的现状和未来发展轨迹.
    • 确定影响国家科学优势的关键因素.

    主要方法:

    • 对过去二十年科学支出的历史数据进行分析.
    • 检查科学事业受欢迎程度的趋势.
    • 评估女性在科学领域的参与率.

    主要成果:

    • 荷兰作为领先的科学支出国,其地位已经下降.
    • 科学职业正在变得越来越不受欢迎.
    • 妇女在科学领域的代表性不足仍然在令人担忧的水平上存在.

    结论:

    • 观察到的趋势可能会导致在不久的将来出现严重的研究人员短缺.
    • 迫切需要注意解决投资和参与率下降的问题,以保持科学卓越.

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    Image-based Lagrangian Particle Tracking in Bed-load Experiments

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    12:21

    Determination of the Friction Coefficients of Icy Pavements Under Different Amounts of Snowfall

    Published on: January 6, 2023

    相关实验视频

    Last Updated: Jul 7, 2026

    Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling
    06:55

    Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling

    Published on: August 5, 2016

    Image-based Lagrangian Particle Tracking in Bed-load Experiments
    10:32

    Image-based Lagrangian Particle Tracking in Bed-load Experiments

    Published on: July 20, 2017

    Determination of the Friction Coefficients of Icy Pavements Under Different Amounts of Snowfall
    12:21

    Determination of the Friction Coefficients of Icy Pavements Under Different Amounts of Snowfall

    Published on: January 6, 2023