There are two places in views. py where we make sure the user associated with a topic matches the currently logged in user. Put the code for this check in a function called check_topic_owner(), and call this function where appropriate.

Acircular pipe of 30mm outside diameter is placed in an airstream at 30 c and latm pressure. the air moves in cross flow over the pipe at 20 m/s, while the outer surface of the pipe is maintained at 110 c. what is the drag force exerted on the pipe per unit length? what is the rate of heat transfer from the pipe per unit length?