The first minerals to crystallize from a cooling magma have a
A) high melting point and a low silica content.
B) low melting point and a high silica content.
C) high melting point and a high silica content.
D) low melting point and a low silica content.
Answer: A
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__________is the separation of material according to density
A) Condensation B) Compression C) Accretion D) Differentiation
A journal bearing has a clearance of 0.5 mm. The journal has a diameter of 100 mm and rotates at 3600 rpm within the bearing. The journal is lubricated by an oil having a density of 800 kg/m3 , a viscosity of 0.01 kg/(ms), and a thermal conductivity of 0.14 W/(m K). Both the journal and the bearing temperatures are maintained at 60°C. Calculate the rate of heat transfer from the bearing and the power required for rotation per unit length.
GIVEN
A journal bearing
Diameter (D) = 100 mm = 0.1 m
Clearance (H) = 0.5 mm = 0.0005 m
Rotational speed (@) = 3600 rpm
Oil properties
? Density (p) = 800 kg/m3
? Viscosity (?) = 0.01 kg/(ms)
? Thermal conductivity (k) = 0.14 W/(m K)
Temperature of both surface (Tb) = 60°C
FIND
(a) The rate of heat transfer from the bearing
(b) The power required for rotation per unit length
ASSUMPTIONS
Steady state
Uniform and constant surface temperatures
Constant fluid properties
SKETCH
A container of water is lifted vertically 3.0 m, then returned to its original position. If the total weight is 30. N, how much work was done?
A) 0.18 kJ B) 45 J C) 90 J D) No work was done. E) 0.90 kJ
Particles (mass of each = 0.20 kg) are placed at the 40-cm and 100-cm marks of a meter stick of negligible mass. This rigid body is free to rotate about a frictionless pivot at the 0-cm end. The body is released from rest in the horizontal position. What is the initial angular acceleration of the body?
a. 12 rad/s2 b. 5.9 rad/s2 c. 8.4 rad/s2 d. 5.4 rad/s2 e. 17 rad/s2