Answer:
 8. 2.75·10^-4 s^-1
 9. No, too much of the carbon-14 would have decayed for radiation to be detected.
Explanation:
8. The half-life of 42 minutes is 2520 seconds, so you have ...
 1/2 = e^(-λt) = e^(-(2520 s)λ)
 ln(1/2) = -(2520 s)λ
 -ln(1/2)/(2520 s) = λ ≈ 2.75×10^-4 s^-1
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9. Reference material on carbon-14 dating suggests the method is not useful for time periods greater than about 50,000 years. The half-life of C-14 is about 5730 years, so at 65 million years, about ...
 6.5·10^7/5.73·10^3 ≈ 11344
half-lives will have passed. Whatever carbon 14 may have existed at the time will have decayed completely to nothing after that many half-lives.
 
        
             
        
        
        
Answer:
20m/second
Explanation:
The reason the answer is 20m/second is because to find the speed of the ball  in this question you have to divide the distance over the time giving you the result of 20m/second
 
        
             
        
        
        
Answer: 71.93 *10^3 N/C
Explanation: In order to calculate the electric field from long wire we have to use the Gaussian law, this is:
∫E*dr=Q inside/εo  Q inside is given by: λ*L then,
E*2*π*r*L=λ*L/εo
E= λ/(2*π*εo*r)= 4* 10^-6/(2*3.1415*8.85*10^-12*2 )= 71.93 * 10^3 N/C
 
        
             
        
        
        
Because the waves in the water with the fan like system.