Complete Question
The complete question is shown on the first uploaded image
Answer:
A

B

C
The correct option is B
Explanation:
From the question we are told that
The refractive index of water is 
The refractive index of ethanol is 
Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

Where c is the speed of light with value 


Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

=> 
=> 
Answer:
As you said you already know, energy cannot be created or destroyed.
Explanation:
You cannot gain energy or lose energy, it can only be converted. So if you start on a 3m high hill and go down it, your potential energy is equal to mgh, and if you get to the bottom of the hill, your KE would be equal to your PE at the top, and when you start going up another hill again, the maximum height you can reach is 3m, because energy cannot be created or destroyed, and your mass and gravitational acceleration are the same, so therefore you can only reach the same height you started from due to the conservation of energy.
Explanation:
the rate at which something occurs or is repeated over a particular period of time or in a given sample
Words less true are seldom if ever spoken.
Answer:
the speed of the tip of a blade 10 s after the fan is turned off is 16.889 m/s.
Explanation:
Given;
diameter of the ceiling fan, d = 90 cm = 0.9 m
angular speed of the fan, ω = 64 rpm
time taken for the fan to stop, t = 28 s
The distance traveled by the ceiling fan when it comes to a stop is calculated as;

The speed of the tip of a blade 10 s after the fan is turned off is calculated as;

Therefore, the speed of the tip of a blade 10 s after the fan is turned off is 16.889 m/s.