In order that nuclear reactions will begin in the core of a protostar it must become
A. hot and of very low density
B. hot and dense
C. cold and dense
D. cold and of very low density
E. infinitely collapsed
Ans: B. hot and dense
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A motor drives a shaft at f 5 10 Hz and delivers P 5 35 kW of power. The allowable shear stress in the shaft is 45 MPa. The minimum diameter of the shaft is approximately:
(A) 35 mm
(B) 40 mm
(C) 47 mm
(D) 61 mm
Laser light sent through a double slit produces an interference pattern on a screen 3.00 m from the slits. If the m = 2 maximum occurs at an angle of 10.7°, at what angle does the m = 8 maximum occur?
a. No m = 8 maximum occurs. c. 56.3° b. 48.0° d. Not enough information is given.
What nuclide has 14 protons and 16 neutrons?
A. 16S B. 14O C. 30Si D. 30S
The design of a part that operates at temperatures up to 150°C (302°F) requires a material that is of low density and corrosion resistant. The stresses on the part are up to 50 MPa (7250psi), and it is required to be able to recycle the material. Which of the following materials might be appropriate?
(a) PE (b) A magnesium alloy (c) Epoxy (d) PEEK