Answer:
The wavelength is 2 meters
Explanation:
The relationship between the frequency, the speed and the wavelength is given by the relation;
v = f × λ
The given parameters are;
The distance of the duck from the edge of the pond = 12 m
The number of ripples produced per second = Frequency, f = 2 Hz
The time it takes the ripple to reach the edge of the pond after travelling past the duck = 3 seconds
Therefore, speed of the wave, v = Distance/time = 12 m/(3 s) = 4 m/s
The wavelength, λ, is therefore;
λ = v/f = (4 m/s)/(2 Hz) = 2 meters.
Because: Some of the work done by the machine is used to overcome the friction created by the use of the machine. ... Work output can never be greater than work input. Machines allow force to be applied over a greater distance, which means that less force will be needed for the same amount of work.
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All frequencies of light in hertz are in between

and

Light with a lower frequency than 4 * 10^14 Hz, are called infrared and can't be seen by human eye. Light with a higher frequency than 8 * 10^14 Hz, are called ultraviolet and can't bee seen by human eye.
Therefore, the maximum frequency of visible light in Hz, is
8 * 10^14 Hz
45 kg * 9.8 m/s^2 = <u>441 N.</u>