Solenoid ?1 has a length L, cross-sectional area A, and N turns. Solenoid ?2 has a length 2L, cross-sectional area 2A, and 2N turns. Which solenoid has the greater magnetic field at its center when equal currents are going through them?
a. ?1
b. ?2
c. Both have the same magnetic field.
d. Since it depends on the values of A and L, none of the above are correct.
c
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A 3.000 kg ball is pitched with a kinetic energy of 20.00 Joules. Then the momentum of the ball is
A. 7.500 kg m/s. B. 8.350 kg m/s. C. 9.450 kg m/s. D. 10.95 kg m/s. E. 12.50 kg m/s.
Saturated steam at 137 kPa condenses on the outside of a 2.6-m-length of copper tubing heating 5 kg/hr of water flowing in the tube. The water temperatures, measured at 10 equally spaced stations along the tube length are
Calculate (a) average overall heat transfer coefficient Uo based on the outside tube area;
(b) average water-side heat transfer coefficient hw (assume steamside coefficient at
hs = 11,000 W/(m2 K)), (c) local overall coefficient Ux based on the outside tube area for
each of the 10 sections between temperature stations, and (d) local waterside coefficients
hwx for each of the 10 sections. Plot all items vs. tube length. Tube dimensions: ID = 2 cm,
OD = 2.5 c. Temperature station 1 is at tube entrance and station 11 is at tube exit.
GIVEN
? Saturated steam condensing on copper tubing with water flowing within
? Steam pressure = 1.35 atm = 136,755 N/m2
? Tube length (L) = 2.6 m
? Water flow rate mw = 5 kg/h = 0.00139 kg/s
? Water temperatures given above as a function of distance along pipe
? Tube diameters
? Di = 2 cm = 0.02 m
? Do = 2.5 cm = 0.025 m
FIND
(a) Average overall heat transfer coefficient based on the outside tube area (Uo)
(b) Average water-side transfer coefficient hw
(c) Local overall coefficient (Ux) for each of the 10 sections
(d) Local water-side coefficient hwx for each of the 10 sections
Plot all items vs. tube length
ASSUMPTIONS
? The steam-side heat transfer coefficient hs = 11,000 W/(m2 K)
? No scaling resistance
? Variation of the specific heat of water is negligible
SKETCH
PROPERTIES AND CONSTANTS
From Appendix 2, Table 13, for saturated steam at 136,755 N/m2: Ts = 107°C
For water at the average temperature of 55°C, the specific heat (cpw) = 4180 J/(kg K)
From Appendix 2, Table 12, the thermal conductivity of copper (k) = 392 W/(m K) at 127°C
How long does it take our solar system to complete one orbit around the Milky Way Galaxy?
A) 100 million years B) 1 million years C) 230 thousand years D) 10 thousand years E) 230 million years
The curved surface of a 50-cm focal length plano-convex lens has a radius of curvature of 30 cm. What is the refractive index of the glass?
What will be an ideal response?