12 V is the f.e.m.

of the battery. The potential difference that is applied to the motor is actually the fem minus the voltage drop on the internal resistance r:

this is equal to the voltage drop on the resistance of the motor R:

so we can write:

and using

and

we can find the current I:
Answer:54.70 N
Explanation:
Given
Gauge Pressure of 
i.e. 
Effective area 
initial Pressure
Gauge Pressure 


Force creates a pressure of
which will be equal to Gauge Pressure





Answer: HP = Horse Power.
Explanation: it is the unit given to tell the motor's particular power and 1hp = 746 watts.
Answer:
Rate of change of area will be 
Explanation:
We have given rate of change of radius 
Radius of the circular plate r = 52 cm
Area is given by 
So 
Puting the value of r and 

So rate of change of area will be 