Answer:
C. The voltage drop across the resistor is 2.1V and nothing about the current through the resistor.
Explanation:
When connected in parallel, voltage across the resistances are the same. So if 2.1V was dropped across the LED then 2.1V was also dropped across the resistor. However, this tells us nothing about the current through the resistor. We can find the current across the resistor if we know the resistance of the resistor, but that's about it. 
If it were a series connection, then the current would have been the same, but the voltage drop were another story.
 
        
             
        
        
        
Answer:
u = - 38.85 m/s^-1
Explanation:
given data:
acceleration = 2.10*10^4 m/s^2
time = 1.85*10^{-3} s
final velocity = 0 m/s
from equation of motion we have following relation
v = u +at
0 =  u + 2.10*10^4 *1.85*10^{-3}
0 = u + (21 *1.85)
0 = u + 38.85
u = - 38.85 m/s^-1
negative sign indicate that the ball bounce in opposite directon
 
        
             
        
        
        
Answer:
The block has an acceleration of 
Explanation:
By means of Newton's second law it can be determine the acceleration of the block.
 (1)
   (1)
Where  represents the net force, m is the mass and a is the acceleration.
 represents the net force, m is the mass and a is the acceleration.
 (2)
  (2) 
The forces present in x are  and
 and  (the friction force):
 (the friction force):

Notice that  subtracts to
 subtracts to  since it is at the opposite direction.
 since it is at the opposite direction.

The forces present in y balance each other:
 
Therefore:
 
  
 (3)
  (3)
But  and writing (3) in terms of a it is get:
 and writing (3) in terms of a it is get: 
 
  

So the block has an acceleration of  .
.
 
        
             
        
        
        
Mid-ocean ridges happen along divergent plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing large volcanic eruptions of basalt.
 
        
             
        
        
        
According to Ideal gasTo solve this problem, the fastest relationship allows us to observe the proportionality between the two variables would be the one expressed in the ideal gas equation, which is

Here
P = Pressure
V = Volume
N = Number of moles
R = Gas constant 
T = Temperature 
We can see that the pressure is proportional to the temperature, then

This relationship can be extrapolated to all the scenarios in which these two variables are related. As the pressure increases the temperature increases. The same goes for the pressure in the atmosphere, for which an increase in this will generate an increase in temperature. This variable can be observed in areas of different altitude. At higher altitude lower atmospheric pressure and lower temperature.