The gap between electrodes in a spark plug is 0.06 cm. In order to produce an electric spark in a gasoline-air mixture, the electric field must reach a value of 3 × 10^6 V/m. What minimum voltage must be supplied by the ignition circuit when starting the car?
1 800 V
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Electromagnetic radiation, or light, travels at speed ___________ m/s
Fill in the blank(s) with correct word
Estimate the rate of heat loss per unit length from a 5 cm ID, 6 cm OD steel pipe covered with high temperature insulation having a thermal conductivity of 0.11 W/(m K) and a thickness of 1.2 cm. Steam flows in the pipe. It has a quality of 99% and is at 150°C. The unit thermal resistance at the inner wall is 0.0026 (m2 K)/W, the heat transfer coefficient at the outer surface is 17 W/(m2 K), and the ambient temperature is 16°C.
GIVEN
Insulated, steam filled steel pipe Diameters
? ID of pipe (Di) = 5 cm=0.05 m
? OD of pipe (Do) = 6 cm=0.06 m Thickness of insulation (Li) = 1.2 cm=0.012 m Steam quality = 99% Steam temperature (Ts) = 150°C Unit thermal resistance at inner wall (A Ri) = 0.026 (m2 K)/W Heat transfer coefficient at outer wall (ho) = 17 W /(m2 K) Ambient temperature (T ) = 16°C Thermal conductivity of the insulation (kI) = 0.11 W /(m K)
FIND
Rate of heat loss per unit length (q/L)
ASSUMPTIONS
1% carbon steel Constant thermal conductivities Steady state conditions
SKETCH
A particle confined to motion along the x axis moves with constant acceleration from x = 2.0 m to x = 8.0 m during a 2.5-s time interval. The velocity of the particle at x = 8.0 m is 2.8 m/s. What is the acceleration during this time interval?
a. 0.48 m/s2 b. 0.32 m/s2 c. 0.64 m/s2 d. 0.80 m/s2 e. 0.57 m/s2
Which of the following best describes the image from a plane mirror?
a. virtual and magnification equal to one b. real and magnification equal to one c. real and magnification less than one d. virtual and magnification greater than one