Aparachutist bails out and freely falls 62 m. then the parachute opens, and thereafter she decelerates at 2.5 m/s2. she reaches the ground with a speed of 2.8 m/s. (a) how long is the parachutist in the air

16.4 s

Explanation:

For AB

initial velocity, u = 0

final velocity, v = ?

acceleration, a = 9.8 m/s^2

distance, s = 62 m

Let the time taken is t.

Use second equation of motion

t = 3.56 s

Use first equation of motion

v = u + at

v = 0 - 9.8 x 3.56

v = - 34.89 m/s

For BC

Let the time taken is t'

initial velocity, v = 34.89 m/s

final velocity, v' = 2.8 m/s

a = 2.5 m/s^2

use first equation of motion

v' = v + a t'

2.8 = 34.89 - 2.5 t'

t' = 12.84 s

So, the total time taken

T = t + t' = 3.56 + 12.84 = 16.4 s

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.

this could be newton#'s law of cooling. the cooling curve is exponential