One of the best indicators of photochemical smog is
a. CO2.
b. HC.
c. O3.
d. NOx.
c
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A cereal box has the dimensions of 0.19 m × 0.28 m × 0.080 m. If there are 3.28 feet per meter, then what is the volume of the box in cubic feet?
a. 0.0043 cubic feet c. 0.046 cubic feet b. 0.15 cubic feet d. 0.0014 cubic feet
A relativistic proton has a momentum of 1.0 × 10-17 kg ? m/s and a rest energy of 0.15 nJ
What is the kinetic energy of this proton? (c = 3.00 × 108 m/s, mproton = 1.67 × 10-27 kg) A) 2.2 pJ B) 1.3 pJ C) 1.6 pJ D) 3.0 pJ E) 2.5 pJ
In an experimental setup in a laboratory, a long cylinder with 5-m diameter, and an electrical resistance heater inside its entire length is cooled with water flowing crosswise over the cylinder at 25oC and a velocity of 0.8 m/s. For these flow conditions, 20 KW/m of power is required to maintain a uniform temperature of 95oC at the surface of the cylinder. When water is not available, air at 25oC is used with the velocity of 10 m/s to maintain the same surface temperature. However, in this case, the cylinder surface heat dissipation rate is reduced to 400 W/m. Calculate the convection heat transfer coefficients for both water and air, and comment on the reason for differences in the value.
GIVEN • A long cylinder with diameter d=5 cm=0.05 m Case A • Crosswise water flow at 25oC and velocity of 0.8 m/s • Power required(qc/L)=20,000 W/m • Surface temperature(Ts)=95 oC Case B • Crosswise air flow at 25oC and velocity of 10 m/s • Power required(qc/L)=400 W/m • Surface temperature(Ts)=95 oC FIND • Convection heat transfer coefficient for both air and water. • Comment on differences in the values. ASSUMPTIONS • The system is in steady state
A 6.0-? and a 12-? resistor are connected in parallel across an ideal 36-V battery. What power is dissipated by the 6.0-? resistor?
A) 48 W B) 220 W C) 490 W D) 24 W