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

=> 
=> 
Normally, when something gets colder, its electrical resistance gets smaller. This is true of component-A in the drawing ... a simple resistor.
The component labeled 'B' has a strange and unusual symbol, and it's not a simple resistor. It's a "thermistor". The word "thermal" always has something to do with heat, and "thermistor" comes from "thermal resistor. These things can be manufactured either way ... using different materials, a thermistor can be manufactured so that its resistance goes UP, or goes DOWN, or doesn'tchange when it gets colder. I'm pretty sure that's what's going on here.
When this circuit gets colder, resistance-A gets smaller, but resistance-B either gets bigger OR doesn't change. Either way, the voltage across B increases. Since the LED is connected directly across B, the current through it depends on that voltage, so the LED gets more current, and becomes brighter, when A and B both get colder.
This circuit could actually be a very useful device. If you took out the LED and put a voltmeter in its place, then the reading on the voltmeter would tell you the temperature of wherever you put the two components A and B.
No force is required to lift that balloon. In fact, force is required to hold it down, and if you let go, it's up, up, and away.
Since the balloon's density is less than the density of the air around it, it's lighter than the air it displaces, there is a net upward buoyant force acting on it, and it floats up !
Answer:
36 N
Explanation:
If the object of mass, m = 8 kg is swung in a horizontal circle of radius, r = 2m = length of string with tangential velocity v = 3 m/s, the tension in the string is the centripetal force which is T = mv²/r
= 8 kg × (3 m/s)²/2 m
= 4 kg × 9 m/s²
= 36 N
Answer:
581 kJ, work was done by the system
Explanation:
According to the first law of thermodynamics:

where
is the change in internal energy of the system
Q is the heat absorbed by the system (positive if absorbed, negative if released)
W is the work done by the system (positive if done by the system, negative if done by the surrounding)
In this problem,


Therefore the work done by the system is

And the positive sign means the work is done BY the system.