Name the following compound: ch2 ≡ ch2

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Matt is driving down 7th street. he drives 150 meters in 18 sec. assuming he doesn’t slow down or speed up, what is his speed?

The image shows a pendulum in simple harmonic motion the pendulum starts at a and swing to e