Avariable mesh screen produces a linear and axisymmet- ric velocity profile as indicated in fig. p5.50 in the air flow through a 2-ft-diameter circular cross-sectional duct. the static pressures upstream and downstream of the screen are 0.2 and 0.15 psi and are uniformly distributed over the flow cross-sectional area. neglecting the force exerted by the duct wall on the flow- ing air, calculate the screen drag force.

The california mussel (mytilus californianus) attaches itself to a rock or other solid surface with a bundle of filaments known as the byssus. imagine that 15.0 j of work is done to stretch the distal end of the byssus. it releases 10.8 j of thermal energy as it relaxes. what is the resilience of the distal end of the byssus?

Cells in the nervous system have a potential difference of 70 mv across the cell membrane separating the interior of the cell from the extracellular fluid. this potential difference is maintained by ion pumps that move charged ions across the membrane. is this an emf? select the correct answer and explanation. 1)no. the ion pumps cannot separate charges; thus, they cannot create a potential difference. 2)yes. the ion pumps cannot separate charges, but they still can create a potential difference. 3)yes. the ion pumps can actively separate charge; thus, they can create a potential difference. 4)no. the ion pumps can separate charges, but they cannot create a potential difference.

Which of these has some mechanical energy? a. an atom b. heat inside earth c. a book on a shelf d. the fire from a lit match