Air at 40 o C flow steadily through the pipe. If P1 = 40 kPa (gauge), P2 = 10 kPa (gauge), D= 3d, Patm = 100 kPa, the average velocity at section 2 is V2 = 25 m/s, and air temperature remains nearly constant. What is the average speed at section 1

Aboxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. the moving boxcar collides and links with the stationary cars and they all move off together along the track. what is the final speed of the cars immediately after the collision? (you may take the mass of each boxcar to be 18,537 kg.)

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Global warming will produce rising sea levels partly due to melting ice caps but also due to the expansion of water as average ocean temperatures rise. to get some idea of the size of this effect, calculate the change in length of a column of water 1.00 km high for a temperature increase of 1.00ºc. note that this calculation is only approximate because ocean warming is not uniform with depth. (answer in ×10^{-3} −3 m)