Just as some chemicals must be given activation energy to start an exothermic chemical reaction, some nuclei must be given nuclear activation energy in order to undergo an exothermic fission
What will be an ideal response?
This is the case. In most cases, a neutron enters the nucleus and bangs about,
setting the nucleus into oscillation like a drop of liquid. Eventually, the nucleus comes apart.
This makes extra neutrons that can go on to break up other nuclei.
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A microphone records sound produced from two speakers in a room with no other sound sources. If the intensity of one of the sound waves at a given location is 0.055 W/m2 and if the microphone receives a minimum intensity of 0.004 
when both speakers are active what is a possible value for the intensity of the other source at the microphone’s location?
A. Need more info to solve.
B. 0.088 
C. 0.051
D. 0.048
According to our present theory of solar system formation, why were solid planetesimals able to grow larger in the outer solar system than in the inner solar system?
A) The solid material that accreted in the outer solar system included ices, while the solid material of the inner solar system consisted only less abundant metal and rock. B) There was more time for accretion in the outer solar system before the solar wind cleared the nebula away. C) The gas in the outer solar system contained a larger proportion of rock, metal, and hydrogen compound than the gas in the inner solar system. D) Gravity was stronger in the outer solar system, allowing more solid material to collect.
A 2.5 × 2.5 m steel sheet 1.5-mm-thick is removed from an annealing oven at a uniform temperature of 425°C and placed in a large room at 20°C in a horizontal position. (a) Calculate the rate of heat transfer from the steel sheet immediately after its removal from the furnace, considering both radiation and convection. (b) Determine the time required for the steel sheet to cool to a temperature of 60°C. Hint: This will require numerical integration.
GIVEN
• Horizontal steel sheet in air
• Sheet dimensions = 2.5 m × 2.5 m × 0.0015 m
• Sheet initial temperature (Tsi) = 425°C = 698 K
• Air temperature (T?) = 20°C = 293 K FIND
(a) The initial rate of heat transfer (q) (b) The time required for the sheet to cool to 60°C (333 K)
ASSUMPTIONS
• The room behaves as a black body at T?
• The steel sheet behaves as a black body (? = 1.0)
• Heat transfer takes place from both top and bottom of the sheet
• The steel is 1% carbon steel
• Heat transfer from the edges of the plate is negligible
SKETCH
PROPERTIES AND CONSTANTS
The Stephan-Boltzmann constant (?) = 5.67 × 10–8 W/(m2 K4)
for 1% carbon steel
Specific heat (cs) = 473 J/(kg K)
Density (?s) = 7801 kg/m3
for dry air at the mean temperature of 496 K (223°C)
Thermal expansion coefficient (?) = 0.00203 1/K
Thermal conductivity (k) = 0.0384 W/(m K)
Kinematic viscosity (?) = 38.7 × 10–6 m2/s
Prandtl number (Pr) = 0.71
Chemically based extraterrestrial life
A) will not need to store information B) may not use DNA to store information but will very likely use a molecule with a similar function C) will certainly use DNA to store information, but with different nucleotides D) will certainly use DNA to store information