Answer: f=150cm in water and f=60cm in air.
Explanation: Focal length is a measurement of how strong light is converged or diverged by a system. To find the variable, it can be used the formula:
= (nglass - ni)(
-
).
nglass is the index of refraction of the glass;
ni is the index of refraction of the medium you want, water in this case;
R1 is the curvature through which light enters the lens;
R2 is the curvature of the surface which it exits the lens;
Substituting and calculating for water (nwater = 1.3):
= (1.5 - 1.3)(
-
)
= 0.2(
)
f =
= 150
For air (nair = 1):
= (1.5 - 1)(
-
)
f =
= 60
In water, the focal length of the lens is f = 150cm.
In air, f = 60cm.
Distance covered by the squirrel to look for an acorn :
d = ( 3 m/s ) × 10 s = 30 m.
Time taken to eat an Acron is 5 seconds.
Time taken to cover distance of 30 m with 2 m/s speed is :

Therefore, total time take to get back to where he started is ( 10+5+15 ) = 30 s.
Hence, this is the required solution.
Answer:

Explanation:
The attached image shows the system expressed in the question.
We can define an expression for the system.
The equivalent equation for the system would be

so, the input signal could be expressed in dB terms
(1)
so the output signal could be expressed as.

The gain should be expressed in dB terms and power in dBm terms so

using the (1) equation to find it in terms of Watts

Answer:
Explanation:
The described situation is is related to vertical motion (and free fall). So, we can use the following equation that models what happens with this rock:
(1)
Where:
is the rock's final height
is the rock's initial height
is the rock's initial velocity
is the angle at which the rock was thrown (directly upwards)
is the time
is the acceleration due gravity in Planet X
Then, isolating
and taking into account
:
(2)
(3)
Finally:
(4) This is the acceleration due gravity in Planet X