Why isn't the Sun shrinking or expanding at present?
A) because the Sun has lived for billions of years
B) Because the Sun is spinning so fast, the centrifugal forces keep the surface of the Sun supported against collapse.
C) because gas pressure balances gravity in the Sun
D) because the Sun is a solid substance
C) because gas pressure balances gravity in the Sun
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Mercury is heated from 100ºF to vapor at 800ºF. Assume hnfg is 122 Btu/lbm at 676ºF and use a cP of 0.032 Btu/lbm ·ºF for liquid mercury and 0.015 for the vapor. Determine the enthalpy change per unit mass and the heat per unit mass.
What will be an ideal response?
What is the heat needed to heat 150 g of water from
to 
(specific heat of water = 4186 J/kg
A. 37.2 kJ B. 44.6 kJ C. 56.5 kJ D. 68.2 kJ E. 75.1 kJ
A 0.650-kg object is swung in a circular path and in a vertical plane on a 0.500-m-length string. If the angular speed at the bottom is 8.00 rad/s, what is the tension in the string when the object is at the bottom of the circle?
a. 27.2 N b. 20.8 N c. 14.4 N d. 6.37 N
Two waves are described by y1 = 6 cos(180t) and y2 = 6 cos(186t) (both in meters). What effective frequency does the resultant vibration have at a point?
a. 92 Hz b. 183 Hz c. 6 Hz d. 3 Hz e. 366 Hz