What use are 21-cm radio waves to galactic astronomers?
A) They bounce off stars like our Sun to let us precisely measure their distances.
B) We can reflect them off the core of the Galaxy.
C) They pick up the cool, dark matter much better than can optical telescopes.
D) They cut through the dusty cocoons to let us watch star birth.
E) Their Doppler shifts let us map the motions and locations of gas in the spiral arms.
E
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The room-temperature yield strength of very-low-carbon steel as a function of the square root of the interstitial solid-solution carbon concentration is shown in Figure 7.12.
(a) Evaluate all of the constants in the equation for the tensile yield strength as a function of solid-solution chemical composition. (b) The maximum equilibrium composition of interstitial carbon possible in ferritic iron is 0.0011 atom fraction (af). If an iron-carbon alloy of this composition could be produced at room temperature, what should the yield strength be? You must solve this problem analytically; you can check your result graphically. (c) If the composition of 0.0011 af of carbon is exceeded, the extra carbon forms iron carbide. If a specimen is produced with 0.0015 af of carbon, do you expect the strength to be given by an extension of the line in the figure? Briefly explain your answer.
Which simplest alcohol is used in race cars as fuel?
a. 2-Propanol b. Ethylene glycol c. Ethanol d. Methanol
A long solenoid has a radius of 4.0 cm and has 800 turns/m. If the current in the solenoid is increasing at the rate of 3.0 A/s, what is the magnitude of the induced electric field at a point 2.2 cm from the axis of the solenoid?
a. 3.3 × 10^?5 V/m b. 3.6 × 10^?5 V/m c. 3.9 × 10^?5 V/m d. 4.2 × 10^?5 V/m e. 6.0 × 10^?5 V/m
Suppose XL > XC in the figure below and, with both switches open, a piece of iron is slipped into the inductor. During this process, what happens to the brightness of the bulb?