Which of the following best summarizes what we mean by dark matter?
A) matter that we have identified from its gravitational effects but that we cannot see in any wavelength of light
B) matter that may inhabit dark areas of the cosmos where we see nothing at all
C) matter consisting of black holes
D) matter for which we have theoretical reason to think it exists, but no observational evidence for its existence
A
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A refrigerator condenser is a heat exchanger that converts a refrigerant from a vapor to a liquid at constant pressure and approximately constant temperature. If ammonia is used as a refrigerant and 10 kg/s is condensed at 25ºC when the surrounding temperature is 20ºC, determine the heat transfer from the refrigerant using data from the Appendix Chart C-7.
What will be an ideal response?
Thermal Expansion: A quantity of mercury occupies 400.0 cm3 at 0°C. What volume will it occupy when heated to 50°C? Mercury has a volume expansion coefficient of 180 × 10-6 K-1.
A. 450 cm3 B. 409.7 cm3 C. 403.6 cm3 D. 401.8 cm3
Organic molecules are:
A) living cells. B) carbon-based. C) silicon-based. D) found only on Earth. E) not found outside our solar system.
A car and driver have a total mass of 945 kg. While rounding a curve on a flat road at a speed of 29 m/s, the net force acting on the car and driver is determined to be 56,767.5 N. The radius of the curve is__________
Fill in the blank(s) with correct word