(a) 
The relationship between frequency and wavelength of an electromagnetic wave is given by
where
is the speed of light
is the frequency
is the wavelength
In this problem, we are considering light with wavelength of
Substituting into the equation and re-arranging it, we can find the corresponding frequency:
(b) 
The period of a wave is equal to the reciprocal of the frequency:
And using 
as we found in the previous part, we can find the period of this wave:
The amount left of a radioactive sample amount N0 if the decay constant is 0.00125 seconds and the time is 180 seconds is 0.7999 N.
<h3>What is half-life?</h3>
The time it takes for half of the original population of radioactive atoms to decay is called the half-life. The relationship between the half-life T1/2 and the decay constant is given by T1/2 = 0.693/λ.
- N=N0e−λt
- given λ = 0.00125 seconds
- t = 180 seconds
- Now putting values.
- N=N0e−λt = 0.799
- N= 0.7999.
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Kinetic energy =1/2 mv^2
<span>m=2ke/v^2 </span>
<span>m=2(34)/3.6^2 </span>
<span>m=5.24 </span>
<span>force normal = mg </span>
<span>=5.24 x 9.8 </span>
<span>force normal = 51.4N
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