Answer:
f1/f2 =W1/W2 = 1/3
.0 f2 = 3f1
As ,
1/F= 1/f1 +1/f2
...1/40 = 1/f1 - 1/3f1
f1=> 80/3 cm
... f2 = 2f1 = 3 x 80/3 = 80 cm
Answer:
The average speed of the earth in its orbit is 
Explanation:
The average distance between the Earth and the Sun is
.
The average speed of the earth in its orbit can be found by the next equation :
(1)
Where r is the radius and T is the period.
In this case, the orbit of the Earth can be considered as a circle
(
) instead of an ellipse.
It takes 1 year to the Earth to make one revolution around the Sun. Therefore, its period will be 365.25 days.
Notice that to express the period in terms of seconds, the following is needed:
⇒ 
Then, equation 1 can be used:


The star looks like a desirable hunk of masculinity to Jane. But to John, the star looks like a wimpy momma's boy who might compete with him for Jane's attention. Jane and John have different impressions of the star because of their gender-specific instincts that have evolved during thousands of millenia of human evolution.
Answer:
See the explanation below
Explanation:
Student c's belief is fulfilled only for the movement of the earth with respect to the sun. But it has no validity or does not exist when it is necessary to explain other physical phenomena with respect to other satellites. For example, how would you explain the phases of the moon, if the Earth is located in the center of the Galaxy?, another serious question regarding the observations made by scientists millions of years ago, where they observed that the distances of the Earth from other planets were changing, with respect to time. If the Earth was in the center, all the planets and the sun would revolve around it preserving a constant distance (radius), at all times.
Other phenomena to explain would be the seasons on Earth, these are due to the axis of inclination of the Earth and the rotation of it around the sun.
Answer:
The new intensity decreases by a factor of 16.
Explanation:
The intensity of sound wave is given by :

P is power
A is area

or
, r is distance from the source
If the distance from the source is increased by a factor of 4, r' = 4r
So,

So, the new intensity decreases by a factor of 16.