Doppler Effect: Sonar is used to determine the speed of an object. A 40.0-kHz signal is sent out, and a 42.0-kHz signal is returned. If the speed of sound is 345 m/s, how fast is the object moving?
A. 6.9 m/s
B. 8.4 m/s
C. 331 m/s
D. 347 m/s
Answer: B
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In partially stabilized zirconia (ZrO2), the addition of materials such as MgO or CaO lowers the temperature of the _________transformation of the tetragonal to the monoclinic phase.
Fill in the blank(s) with the appropriate word(s).
A long concrete beam is to undergo a thermal test to determine its loss of strength in the event of a building fire. The beam cross section is triangular as shown in the sketch. Initially, the beam is at a uniform temperature of 20°C. At the start of the test, one of the short faces and the long face are exposed to hot gases at 400°C through a heat transfer coefficient of 10 W/(m2 K) and the remaining short face is adiabatic. Produce a graph showing the highest and lowest temperatures in the beam as a function of time for the first 1 hour of exposure. For the concrete properties, use k = 0.5 W/(mK) and n = 5 x 10–7 m2/s. Use a node spacing of 4 cm. and use an explicit difference scheme.
GIVEN
Concrete beam suddenly exposed to hot gases
FIND
(a) Highest and lowest temperatures in the beam as a function of time
SKETCH
How long a star can remain on the main sequence depends upon its __________
Fill in the blank(s) with correct word
What type of prevention seeks to minimize the severity of the illness or the damage due to an injury-causing event once the event has occurred?
What will be an ideal response?