Answer:
The observer detects light of wavelength is 115 nm.
(b) is correct option
Explanation:
Given that,
Wavelength of source = 500 nm
Velocity = 0.90 c
We need to calculate the wavelength of observer
Using Doppler effect
Where, 
Hence, The observer detects light of wavelength is 115 nm.
The answer is; Irregular.
I already answered this quesiton. The fact is that there are only two kind of poles and since the two taped poles of the magnets labeled A and B attracts one to each other, we know that the two taped poles of the first two magnets are oppsosite.
Then, the taped pole of the third magnet has to be equal to one of the first two taped poles and opposite to the other of the first two taped poles.
That drives you to conclude (predict) that when she brings the taped end of the third magnet (magnet C) near each of the first two magntes, in one case they will attract each other and in the other case they will repele mutually.
Answer;
It does not have an hypothesis
Explanation;
The goal of descriptive investigation is to describe. It should provide factual, accurate and systematic descriptions of phenomena without attempting to infer causal relationships. It does not answer questions about the how, when, or why a particular phenomenon occurred.
A descriptive investigation includes a question but no hypothesis. Observations are recorded, but no comparisons are made and no variables are manipulated.
Answer:
The mass of the solid cylinder is 
Explanation:
From the question we are told that
The radius of the grinding wheel is 
The tangential force is 
The angular acceleration is 
The torque experienced by the wheel is mathematically represented as
Where I is the moment of inertia
The torque experienced by the wheel can also be mathematically represented as
substituting values
So
So
This moment of inertia can be mathematically evaluated as
substituting values
=>
