Earth's lower atmosphere contains negative and positive ions that are produced by radioactive elements in the soil and cosmic rays from space. in a certain region, the atmospheric electric field strength is 118 v/m and the field is directed vertically down. this field causes singly charged positive ions, at a density of 503 cm-3, to drift downward and singly charged negative ions, at a density of 628 cm-3, to drift upward (see the figure). the measured conductivity of the air in that region is 2.69 × 10-14 (ω-m)-1. calculate (a) the magnitude of the current density and (b) the ion drift speed, assumed to be the same for positive and negative ions.

the electric field is a “force field” around a charged object that illustrates the direction the electric force would push an imaginary 

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

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answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s