A stationary source S generates circular outgoing waves on a lake. The wave speed is 4.0 m/s and the crest-to-crest distance is 80 cm. A boat is approaching the source at 1.0 m/s. The frequency of these waves, as observed by a person in the boat, is A. 3.2 Hz. B. 3.8Hz. C. 6.3 Hz. D. 6.7 Hz. E. 5.0 Hz.

correct option is C.

Explanation:

As the source is stationary. And the observer is moving towards the source. It leads to Doppler effect. The frequency measure by the observer will be higher as is it moving towards the source. Lets find out the value of frequency.

The formula for this case is,

where

= c/λ

λ = wavelength

by putting it in above equation,

v = c/λ ( 1+ v/c)

  =

   = 6.3 Hz.

So the correct option is C.

emily ruth's annual premium is $1058.50

step-by-step explanation:

emily ruth is a female of 27 years age purchasing 20 year endowment insurance with face value $25000.

from the given table,

for females, the age of a male 3 years younger should be used.

so, we have to check for 24 year male for 20 year endowment.

it is 42.34 for every $1000 face value.

for a face value of $25000,

it is 25 * 42.34 = $1058.50

∴ emily ruth's annual premium is $1058.50

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