Since 1983 the standard meter has been defined in terms of which of the following?
a. specific alloy bar housed at Sevres, France
b. wavelength of light emitted by krypton-86
c. distance from the Earth's equator to the North Pole
d. the distance light travels in a certain fraction of a second
e. None of the above
d
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At what temperature would the rms speed of H2 molecules equal the earth's escape speed (11,200 m/s)?
A. 
K
B. 
K
C. 
K
D. 
K
A pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm, and 96 cm but does not resonate at any wavelengths longer than these. This pipe is
A) open at both ends. B) open at one end and closed at the other end. C) closed at both ends. D) We cannot tell because we do not know the frequency of the sound.
You are driving in your car with a sack of groceries in the seat next to you. You see a light change and you slow down and the sack remains on the seat. Suddenly the car in front of you slams on the brakes, and you are forced to brake harder
The groceries slide off the seat. Explain what happened.
What are two advantages of CCDs over photographic films for astronomy?
What will be an ideal response?