A concrete wall is 15.0 cm thick and has an area of 10.0 m2. A layer of wood that is 2.50 cm thick is placed over the wall to reduce the loss of heat by thermal conduction. The coefficient thermal conductivity of concrete is 1.70 W/m and the coefficient of thermal conductivity of wood is 0.0400 W/m What is the effective coefficient of thermal conductivity of the wood on concrete system?

A. 0.245 W/m

B. 1.22 W/m

C. 1.65 W/m

D. 2.02 W/m

E. 2.34 W/m


A. 0.245 W/m

Physics & Space Science

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Relative Velocity: On a calm day with no wind, you can run a 1500-m race at a velocity of 4.0 m/s. If you run the same race on a day when you have a constant headwind that slows your speed by 2.0 m/s, how much time would it take you to finish the race?

A. 250 s B. 750 s C. 1125 s D. 9000 s

Physics & Space Science

What is the sign of these fields’ divergence at point P on each diagram? (Hint: Draw a cross-sectional view of a small div-meter centered on the point in question, and sketch the electric field vectors at the midpoint of each of the div-meter’s four sides in the drawing’s plane. Don’t worry about how we might create such a field.

A. The divergence is positive. B. The divergence is negative. C. The divergence is zero.

Physics & Space Science

Iron is classified as a(n) ______________.

Fill in the blank(s) with the appropriate word(s).

Physics & Space Science

Molecular Speeds: A flask contains a mixture of argon and neon gases at a stabilized temperature. The root-mean-square speed of the argon gas is determined to be 1.21 km/s. What is the root-mean-square speed of the neon gas? The atomic mass of argon is 39.95 g/mol, and that of neon is 20.18 g/mol.

Fill in the blank(s) with the appropriate word(s).

Physics & Space Science