In fair weather, the electric field in the air at a particular location immediately above the Earth’s surface is 120 N/C directed downward. (a) What is the surface charge density on

the ground? Is it positive or negative? (b) Imagine the surface charge density is uniform

over the planet. What then is the charge of the whole surface of the Earth? (c) What is the

Earth’s electric potential due to this charge? (d) What is the difference in potential between

the head and the feet of a person 1.75 m tall? (Ignore any charges in the atmosphere.)

(e) Imagine the Moon, with 27.3% of the radius of the Earth, had a charge 27.3% as large,

with the same sign. Find the electric force the Earth would then exert on the Moon.

(f) State how the answer to part (e) compares with the gravitational force the Earth exerts

on the Moon.

Acar is going 5m/s around a bend with a radius of 10m/s why is the accelerant?

Orque can be calculated by multiplying the force (n) applied at 90? to the lever arm at a distance (m) from the pivot point (point of rotation), the compound si unit for the torque is n? m. if the force (at 90? to the lever arm) applied is 15 n and it is applied at 2.0 m from the pivot point (point of rotation), what is the torque on the lever?

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