Resistivity measurements on the leaves of corn plants are a good way to assess stress and overall health. The leaf of a corn plant has a resistance of 2.3 MΩ measured between two electrodes placed 20 cm apart along the leaf. The leaf has a width of 2.9 cm and is 0.20 mm thick.
1. What is the resistivity of the leaf tissue?
Express your answer to two significant figures and include the appropriate units.
rho=
2. Is this greater than or less than the resistivity of muscle tissue in the human body?
(A) greater or
(B) less

Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. provide a plausible explanation for this situation (with supporting calculations) by considering a room whose air temperature is maintained at 20â°c throughout the year, while the walls of the room are nominally at 27â°c and 14â°c in the summer and winter, respectively. the exposed surface of a person in the room may be assumed to be at a temperature of 32â°c throughout the year and to have an emissivity of 0.90. the coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 w/m2 â‹…â‹… k. what is the ratio of the thermal resistance due to convection to the thermal resistance due to radiation in the summer? what is the ratio of thermal resistances in the winter

Determine the force the sun exerts on an object with a mass of 80.0 kg if that object is on the earth. what is the force exerted by the moon on the same object? what is the force the earth exerts on it?

Which of the following are forms of phase changes a. freezing b. condensation c. heating d. exchanging