When Sam presses the brake lever, a pair of rubber shoes  clamps onto the metal inner rim of the front and back wheels. As the brake shoes rub  against the wheels, friction is caused and  the kinetic energy possessed by the vehicle is converted into heat which slows down the vehicle.
 
        
             
        
        
        
Answer:
Difference threshold or also Just Noticeable Difference
Explanation:
The above mentioned case between room mates, where one room mate was able to detect a minute change in volume shows an instance of the difference threshold.
Difference threshold can be defined as stimulation at its minimum level that can be detected by an individual almost 50 % of the times. 
It is the lowest possible level of sound that is detectable by a person.
That is what happened in the mentioned case that when the volume was increased from 14 to 15, Amber was able to detect it.
 
        
             
        
        
        
The total amount of energy per hour is 
Explanation:
In this problem we are told that the amount of energy reaching a square meter in the United States per hour is

The total surface area of the United States is

And converting into squared metres,

Therefore, the total energy reaching the entire United States per hour is given by:

Learn more about energy and power:
brainly.com/question/7956557
#LearnwithBrainly
 
        
             
        
        
        
To solve this problem we will use the linear motion description kinematic equations. We will proceed to analyze the general case by which the analysis is taken for the second car and the tenth. So we have to:

Where,
x= Displacement
 = Initial velocity
 = Initial velocity
a = Acceleration
t = time 
Since there is no initial velocity, the same equation can be transformed in terms of length and time as:

 For the second cart

When the tenth car is aligned the length will be 9 times the initial therefore:

When the tenth car has passed the length will be 10 times the initial therefore:

The difference in time taken from the second car to pass it is 5 seconds, therefore:

From the first equation replacing it in the second one we will have that the relationship of the two times is equivalent to:


From the relationship when the car has passed and the time difference we will have to:



Replacing the value found in the equation given for the second car equation we have to:

Finally we will have the time when the cars are aligned is


The time when you have passed it would be:


The difference between the two times would be:

Therefore the correct answer is C.