A window glass that is 0.5 cm thick has dimensions of 3 m by 1.5 m. The thermal conductivity of this glass is 0.8 W/m ? K
If the outside surface of the glass is at -10°C and the inside surface is at 20°C, how much heat flows through the window in every hour?
A) 50 MJ
B) 60 MJ
C) 70 MJ
D) 80 MJ
D
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Bert says that a charged particle in a vacuum can travel in a helix only if a uniform electric field and a uniform magnetic field are both present and both parallel to the axis of the helix. Stuart says that only a magnetic field with a component parallel to the axis of the helix is needed. Which one, if either, is correct, and why?
a. Bert, because the charged particle's velocity can have a vertical component only if an electric field in the vertical direction is present. b. Stuart, because a component of velocity in the vertical direction is not changed by a vertical component of a magnetic field. c. Bert, because a component of velocity in the vertical direction is changed by a vertical component of a magnetic field. d. Stuart, because an electric field in the vertical direction would cause the particle to come to a complete stop. e. Neither, because particles cannot move in helical paths in the presence of magnetic and electric fields.
A 4.2-L flask of ideal neon gas (which is monatomic) is at a pressure of 3.3 atm and a temperature of 450 K. The atomic mass of neon is 20.2 g/mol
How many neon atoms are in the flask? (R = 8.31 J/mol ? K, 1 atm = 101 kPa, NA = 6.022 × 1023 molecules/mol) A) 2.3 × 1023 B) 2.3 × 1022 C) 6.9 × 1023 D) 2.3 × 1025 E) 6.9 × 1022
Calculate (0.82 + 0.042) × (4.49 × 10^3), keeping only significant figures
a. 3870.8 c. 3879 b. 3870 d. 3900
A conducting loop in the form of a circle is placed perpendicular to a magnetic field of 0.50 T. If the area of the loop decreases at a rate of 3.0 × 10-3 m2/s, what is the induced emf in the loop?
A) 1.7 mV B) 4.3 mV C) 5.5 mV D) 0 mV E) 1.5 mV