Is this the answer for the question or is there a question for us?
Answer:
Minimum speed will be equal to 2.213 m/sec
Explanation:
We have given radius of the r = 2 m
Coefficient of friction 
At minimum speed frictional force will be equal to centripetal force
So 
So the minimum speed will be equal to 2.213 m/sec
The isotopes half life is 2 hours
Since given the following :
time = 8 hours × 3600s/hr = 28800 seconds
A₀ = 80 Bq as the first registration of detector counts per second
A = 5 Bq as the registration of detector counts per second eight hours later
Using the formula:
∴ A = A₀ e^-λt
∴ A/A₀ = e^-λt
∴ ln (A/A₀) = -λt
∴ λ = -ln (A/A₀) /t = ln2 / t_{1/2}
∴ t_{1/2} = -ln2 / ln(A/A₀) (t)
∴ t_{1/2} = -ln2 / ln(5/80) (8 hours) = 2 hours
I think the answer is C. Remaining constant
The answer is b) false. Stars are mainly classified by their spectra (the elements they absorb) and their temperature.
