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相关概念视频

Rocket Propulsion in Empty Space - I01:13

Rocket Propulsion in Empty Space - I

The driving force for the motion of any vehicle is friction, but in the case of rocket propulsion in space, the friction force is not present. The motion of a rocket changes its velocity (and hence its momentum) by ejecting burned fuel gases, thus causing it to accelerate in the direction opposite to the velocity of the ejected fuel. In this situation, the mass and velocity of the rocket constantly change along with the total mass of ejected gases. Due to conservation of momentum, the rocket's...
Rocket Propulsion In Empty Space - II01:12

Rocket Propulsion In Empty Space - II

The motion of a rocket is governed by the conservation of momentum principle. A rocket's momentum changes by the same amount (with the opposite sign) as the ejected gases. As time goes by, the rocket's mass (which includes the mass of the remaining fuel) continuously decreases, and its velocity increases. Therefore, the principle of conservation of momentum is used to explain the dynamics of a rocket's motion. The ideal rocket equation gives the change in velocity that a rocket experiences by...
Rocket Propulsion in Gravitational Field - I01:20

Rocket Propulsion in Gravitational Field - I

Rockets range in size from small fireworks that ordinary people use to the enormous Saturn V that once propelled massive payloads toward the Moon. The propulsion of all rockets, jet engines, deflating balloons, and even squids and octopuses are explained by the same physical principle: Newton's third law of motion. The matter is forcefully ejected from a system, producing an equal and opposite reaction on what remains.
The motion of a rocket in space changes its velocity (and hence its...
Rocket Propulsion in Gravitational Field - II01:03

Rocket Propulsion in Gravitational Field - II

A rocket's velocity in the presence of a gravitational field is decreased by the amount of force exerted by Earth's gravitational field, which opposes the motion of the rocket. If we consider thrust, that is, the force exerted on a rocket by the exhaust gases, then a rocket's thrust is greater in outer space than in the atmosphere or on a launch pad. In fact, gases are easier to expel in a vacuum.
A rocket's acceleration depends on three major factors, consistent with the equation for the...
Heart Sounds01:15

Heart Sounds

Heart sounds are generated by the turbulence in blood flow due to the closing of heart valves. These sounds are best perceived slightly away from the valves, where the blood flow disseminates the sound.
Auscultation is the process of listening to these internal body sounds using a stethoscope. The heart produces four types of sounds, but only two—S1 and S2—can usually be heard with a stethoscope.
S1, also known as the "lub" sound, is caused by the closure of atrioventricular (A-V) valves at the...
Impact: Problem Solving01:26

Impact: Problem Solving

In an experiment conducted during a Mars mission, a rover propels a projectile with an initial velocity, and the projectile rebounds after colliding with the Martian surface. To ascertain the maximum height attained by the projectile after this collision, the known restitution coefficient and acceleration due to gravity are employed.
By designating the launch point as the origin and utilizing kinematic equations, the vertical component of the projectile's velocity at the point of impact is...

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相关实验视频

Updated: Jun 21, 2026

Bringing the Visible Universe into Focus with Robo-AO
10:35

Bringing the Visible Universe into Focus with Robo-AO

Published on: February 12, 2013

在太空中的阿波罗火箭的声音.

D Cotten, W L Donn

    Science (New York, N.Y.)
    |February 12, 1971
    PubMed
    概括

    来自阿波罗火箭的低频声波在百慕大被检测到. 这些来自高海拔的信号是由稀释大气中的冲击形成理论解释的.

    科学领域:

    • 声学 声学 在声学方面
    • 航空航天工程 航空航天工程
    • 大气物理学 大气物理学

    背景情况:

    • 低频声音现象可能是由高速大气事件产生的.
    • 之前的研究已经探索了火箭发射的声学信号,但高空来源仍然不太了解.

    研究的目的:

    • 调查阿波罗火箭发射期间记录的低频声音的起源和特征.
    • 为了确定这些声信号是否可以通过大气冲击波理论来解释.

    主要方法:

    • 在阿波罗火箭穿越期间,百慕大三方阵列记录的声学数据的分析.
    • 信号特征 (连贯性,速度,到达时间,频率) 与火箭轨道数据的比较.
    • 动力理论用于稀释大气中的冲击形成和气体动力学冲击理论的应用.

    主要成果:

    • 连贯的低频声信号多次被记录下来,与阿波罗火箭在188公里高度发射相吻合.
    • 信号表现出高,超音速的轨迹速度和一致的特征 (外观,频率,到达时间) 跨阵列.
    • 观察到的表面压力变化与高海拔冲击形成的理论模型一致.

    结论:

    • 记录的低频声音是绝对归因于高空的阿波罗火箭飞行器.

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    Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown
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    Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

    Published on: February 14, 2014

    Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface
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    Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface

    Published on: July 30, 2020

    相关实验视频

    Last Updated: Jun 21, 2026

    Bringing the Visible Universe into Focus with Robo-AO
    10:35

    Bringing the Visible Universe into Focus with Robo-AO

    Published on: February 12, 2013

    Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown
    09:40

    Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

    Published on: February 14, 2014

    Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface
    06:14

    Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface

    Published on: July 30, 2020

  • 综合动力学理论和气体动力学方法成功地解释了观察到的声学现象和表面压力效应.