Which of the following statements is correct about the experiment that first measured the charge of the electron?

A. The oil drop is suspended because there are no forces acting on the drop
B. The important result was that Coulomb attraction made all of the oil drops the same mass, regardless of type of oil
C. The mass of the drop was determined by measuring its terminal velocity
D. The value for electron charge had an experimental error of about 35%
E. Light hitting the oil drops manipulated their movement in a way to create an interference pattern.

C.
The terminal velocity of the drop occurs when the frictional drag force—which depends on velocity—balances exactly the gravitational force and the drop falls at constant velocity. The radius of the drop is related to the terminal velocity, and knowing the density of the oil can give the mass.

Physics & Space Science

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Design (i.e., determine the overall area and a suitable arrangement of shell and tube passes) a tubular-feed water heater capable of heating 2,300 kg/h of water from 210C to 90°C. The following specification are given (a) saturated steam at 920 kPa absolute pressure is condensing on the outer tube surface, (b) heat transfer coefficient on steam side is 6800 W/(m2 K), (c) tubes are of copper, 2.5 cm, 2.3-cm-ID, 24 m long, and (d) water velocity is 0.8 m/s.

GIVEN
• A tubular-feed water heater, condensing saturated steam on outside
• Water flow rate m w= 2300 kg/h = 0.639 kg/s
• Water temperatures Tw,in = 21°C Tw,out = 90°C
• Steam temperature = 920 kPa absolute
• Heat transfer coefficient on steam side h o= 6800 W/(m2 K)
• Tubes are copper Di = 2.3 cm = 0.023 m Do = 2.5 cm = 0.025 m
• Water velocity (V) = 0.8 m/s
FIND
• The transfer area (A) and a suitable arrangement of shell and tube passes
SKETCH
Assuming a single shell pass and two tube passes

PROPERTIES AND CONSTANTS
the thermal conductivity of copper at 127°C (k) = 392 W/(m K)
the saturation temperature of steam at 920 kPa (Ts) = 176°C
for water at the average temperature of 56°C
Density (?) = 984.9 kg/m3
Specific area (cpw) = 4181 J/(kg K)
Thermal conductivity (kw) = 0.653 W/(m K)
Kinematic viscosity (?) = 0.510 × 106 m2/s
Prandtl number (Pr) = 3.23

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If the electric field is zero everywhere inside a region of space, the potential must also be zero in that region

A) True B) False

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In terms of a combination of three other symbols, the wavelength (?) of a moving particle is equal to ______________

Fill in the blank(s) with correct word

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An adiabatic process occurs when

A) no thermal energy enters or leaves the system. B) thermal energy leaving a system is greater than thermal energy entering a system. C) thermal energy leaving a system is less than thermal energy entering a system. D) none of these

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Physics & Space Science