Fa wave has a wavelength of 9 meters and a period of 0.006, what is the velocity of the wave? a. 1,200 m/s b. 1,500 m/s c. 1,800 m/s d. 1,285 m/s

1500 m/sec. ( b )

Solution:

V= f (λ)

Speed = frequency. Wavelength  

And frequency = 1/time period

First we will find the frequency :

Frequency = 1/time period

1/0.006 = 166.67 Hz

Using this in the equation:

Speed = frequency. Wavelength  

V= f (λ)

9 × 166.67  

= 1500.03 ≈ 1500

V (Speed) = 1500 m/s.

Note: Do not forget to mention the units or otherwise they may cost you marks!

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.