A solid concrete wall has dimensions 4.0 m × 2.4 m and is 30 cm thick. The thermal conductivity of the concrete is 1.3 W/m ? K, and it separates a basement from the ground outside
The inner surface of the wall is at 18°C, and the outside surface is at 6°C. How much heat flows through the wall every hour? A) 1.8 MJ
B) 1.8 kJ
C) 500 J
D) 5.0 MJ
E) 5.0 kJ
A
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Which of the following properties of a star can be measured directly, during a single night at the telescope?
A) parallax B) distance C) apparent brightness D) luminosity
The "redshift" of a galaxy refers to the rate
A) at which is receding. B) at which it is approaching. C) at which it is spinning. D) of its fusion.
In a 120-volt circuit, 120 joules of
1) charge move each second, which makes up the current, 2) energy are given to each unit of charge that makes up the current, 3) energy are given to each unit of resistance in the circuit, and if the current is 1 ampere, then 4) 1 unit of charge per second passes any point in the circuit. 5) 120 units of charge per second pass any point in the circuit. 6) the resistance of the circuit is 1 ohm.
Sometimes when you look into a curved mirror you see a magnified image (a great big you) and sometimes you see a diminished image (a little you). If you look at the bottom (convex) side of a shiny spoon, what will you see?
A) You won't see an image of yourself because no image will be formed. B) You will see a little you, upside down. C) You will see a little you, right side up. D) You will see a little you, but whether you are right side up or upside down depends on how near you are to the spoon. E) You will either see a little you or a great big you, depending on how near you are to the spoon.