The boundary shown is that of a uniform magnetic field directed in the positive z direction. An electron enters the magnetic field with a velocity pointing along the x axis and exits 0.63 ?s later at point A. What is the magnitude of the magnetic field?
A. 18 ?T
B. 14 ?T
C. 28 ?T
D. 34 ?T
E. 227 ?T
Answer: B
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An example of a heat mover is
a. a refrigerator. b. an air conditioner. c. a heat pump. d. all of the above. e. none of the above.
After landing on an unexplored Klingon planet, Spock tests for the direction of the magnetic field by firing a beam of electrons in various directions and by recording the following observations: Electrons moving upward feel a magnetic force in
the northwest direction. Electrons moving horizontally toward the north are pushed downward. Electrons moving horizontally toward the southeast are pushed upward. Mr. Spock therefore concludes that the magnetic field at this landing site is in which direction? A) toward the east B) toward the northeast C) toward the southwest D) toward the southeast E) toward the west
In the reaction 
how much energy is released or absorbed? The mass of 4He is 4.0026032 u, the mass of 9Be is 9.0121821 u, the mass of n is 1.0086649 u, and the mass of 12C is 12.0000000 u.
A. 4.21 MeV absorbed B. 4.21 MeV released C. 5.70 MeV absorbed D. 5.70 MeV released E. 6.34 MeV released
In the heat treating process in a sheet-metal manufacturing plant, brass plates are annealed by first heating them in an industrial furnace oven the inside of which is maintained at a constant uniform temperature of 550°C. If the surface of the brass plate, which has a thickness of 2.5 cm, is initially at a uniform temperature of 25°C, determine the time required for heating the plate surface to 300°C after the plate has been placed inside the oven. Consider that heat transfer from the oven gases to the plate is by convection and that 135 ch = W/m2 K.
GIVEN
• Brass plate of thickness L=2.5 cm=0.025 m
• Initial temperature of the plate (To) = 25°C
• Heat treating oven temperature (T?) = 550°C
• Convective heat transfer coefficient ( ch ) = 135 W/(m2 K)
FIND
• The time required for the plate to reach temperature of 3000C.
ASSUMPTIONS
• Constant thermal conductivity
• End effects are negligible
SKETCH
PROPERTIES AND CONSTANTS
As per the information provided:
Thermal conductivity (k) = 50 W/(m K) Specific heat (c) = 460 J/(kg K) Density (?) = 7865 kg/m3