Define and explain the meaning of DENSITY
What will be an ideal response?
Density expresses how much mass is contained in a unit volume:
i.e., Density = Mass/Volume
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Conservation of Momentum: Two friends are standing on opposite ends of a canoe that is initially at rest with respect to a frictionless lake. The person in the front throws a very massive ball toward the back, and the person in the back catches it. After the ball is caught, the canoe is
A. moving backward. B. stationary. C. moving forward.
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
Two protons attract each other gravitationally and repel each other electrically. The stronger of these two forces is
A) gravitation. B) electrical. C) neither of these
Consider a situation where you exert a force F on a crate of mass m, moving it at a speed v a distance d across a floor in a time interval t. The potential energy of the crate is __________
Fill in the blank(s) with correct word