Answer:
We have to show surface area  ,with few conditions that is by considering Force
,with few conditions that is by considering Force  and Pressure
 and Pressure  to be respectively.
 to be respectively.
Explanation:
The atmospheric pressure is  on Earth's surface.
 on Earth's surface.
 The magnitude of the force exerted on a person by the atmosphere is  .
.
Now to calculate surface area we can find it from  and re-arranging it to.
 and re-arranging it to.

So plugging the values, 
Surface area 
Hence from the above calculations we can say that surface area is  .
.
So the surface area of an average person can be said to have  , using the concept of pressure and force.
, using the concept of pressure and force.
 
        
                    
             
        
        
        
Answer:
a)η = 69.18 %
b)W= 1210 J
c)P=3967.21 W
Explanation:
Given that
Q₁ = 1749 J
Q₂ = 539  J
From first law of thermodynamics 
Q₁   = Q₂ +W
W=Work out put
Q₂=Heat rejected to the cold reservoir
Q₁ =heat absorb by hot  reservoir
W= Q₁- Q₂ 
W= 1210 J
The efficiency given as



η = 69.18 %
We know that rate of work done is known as power


P=3967.21 W
 
        
             
        
        
        
As we know that here no air resistance while ball is moving in air
So here we will say that
initial total energy = final total energy

here we know that
 (as it will be on ground at initial and final position)
 (as it will be on ground at initial and final position)
so we will say

since mass is always conserved
so we will say that final speed of the ball must be equal to the initial speed of the ball
so we have

 
        
                    
             
        
        
        
Answer:
a) 35.44 mm
b) 17.67 mm
Explanation:
u = Object distance =  3.6 m
v = Image distance
f = Focal length = 35 mm
 = Object height = 1.8 m
= Object height = 1.8 m
a) Lens Equation

The CCD sensor is 35.34 mm from the lens
b) Magnification


The person appears 17.67 mm tall on the sensor
 
        
             
        
        
        
Explanation:
Volume of 10 coins = 100ml - 75ml = 25ml
Volume of 1 coin = 25ml / 10 = 2.5ml
The average volume of each coin is 2.5ml.