A hiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake.
1 answer:
Answer:
L = 499 m
Explanation:
- If we assume that the speed of sound is constant, that travels along a straight line, and that the echo is instantaneous, we can find the total distance travelled by the sound, as follows, just applying the definition of average velocity:
- If we assume that the time needed to reach to the cliff, is the same used for the return travel, the length of the lake will be exactly half of the total distance calculated:
- The length of the lake is 499 m.
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Answer:
Explanation:
The resistance of a wire is given by:
where
is the resistivity of the material
L is the length of the wire
A is the cross-sectional area of the wire
1) The first wire has length L and cross-sectional area A. So, its resistance is:
2) The second wire has length twice the first one: 2L, and same thickness, A. So its resistance is
3) The third wire has length L (as the first one), but twice cross sectional area, 2A. So, its resistance is
By comparing the three expressions, we find
So, this is the ranking of the wire from most current (least resistance) to least current (most resistance).
Answer:
The intensity is
Explanation:
From the question we are told that
The intensity of the unpolarized light is
The angle between the ideal polarizing sheet is
Generally the intensity of light emerging from the first polarizer is mathematically represented as
substituting values
Then the intensity of incident light emerging from the second polarizer is mathematically represented by Malus law as
substituting values