为什么打雷闪电时，总是先看到闪光、过一会儿才听到雷声？
Why do you always see lightning flash before hearing the thunder?
光在空气中的速度约每秒30万公里，而声音只有约340米每秒，差距极大。同一事件的光几乎瞬间到达，声音却要跑好几秒，所以先见光后闻声。
Light travels about 300,000 km per second in air while sound moves only about 340 m per second, a huge gap. The light from the same event arrives almost instantly, but the sound takes seconds, so you see the flash before the thunder.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#光速 #声速 #波动物理
驻波和行波有什么区别？
What is the difference between standing and traveling waves?
行波把能量和信息沿传播方向输送，波形整体移动；驻波由两列反向行波叠加而成，某些点始终不动（波节），整体不向前传播能量。乐器弦上的振动就是典型的驻波。
A traveling wave carries energy and information along its direction, with the waveform moving as a whole; a standing wave forms from two opposite traveling waves and has fixed nodes where motion is always zero, transporting no net energy forward. The vibration on a musical string is a classic standing wave.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#驻波 #行波 #波节
什么是波？
What is a wave?
波是振动或扰动在空间中的传播，本身不搬运物质，只传递能量和信息。它用波长、频率、振幅和速度来描述。声波、水波和光波虽然介质不同，但都遵循共同的波动规律。
A wave is the propagation of a vibration or disturbance through space; it transports no matter, only energy and information. It is described by wavelength, frequency, amplitude, and speed. Sound, water, and light waves differ in medium yet follow common wave laws.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#波 #振动 #传播
声音和光有什么根本不同？
What is the fundamental difference between sound and light?
声音是物质介质中的机械纵波，需要空气、水等介质才能传播，且速度远低于光速。光是电磁横波，可在真空中以约30万公里每秒传播。所以太空中能看见爆炸却听不到声音。
Sound is a mechanical longitudinal wave in a material medium and needs air or water to travel, at a speed far below light. Light is an electromagnetic transverse wave that propagates through vacuum at about 300,000 km/s. So in space you could see an explosion but hear nothing.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#声音 #光 #波
多普勒效应如何解释红移和蓝移？
How does the Doppler effect explain redshift and blueshift?
当波源与观察者相互靠近时，接收到的频率升高（蓝移）；相互远离时频率降低（红移）。光和声音都满足这一规律。天文学家借此测出恒星和星系的退行速度，发现了宇宙膨胀。
When a source and observer approach each other, the received frequency rises (blueshift); when they recede, it falls (redshift). Both light and sound follow this rule. Astronomers use it to measure stars' and galaxies' recession speeds, revealing the universe's expansion.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#多普勒 #红移 #蓝移