Wednesday, 10 August 2011

MEASUREMENT AND UNITS

SCIENTIFIC NOTATION
Exercise:
1)      86kN   = ________ mN
       
 Answer :
                  86=8.6 x 10
                       =8.6x10x103/10-3
                                    =8.6 x 107
                 
2)      45kMJ-1     =  _________m3
    
Answer:
                45=4.5x10
                    =4.5 x 103=4.5 x 104 /60x60
                                      =4.5 x 104 /3600
                                       =1.25 x 10

        3)78 g cm min-2  = _________kgms-1
                          Answer:
                               =78 / 1000 kg cm min -2
                               =0.078 /100 kg m min-2
                                                 =0.00078/minkgm
                               =(0.00078 /60 s)2  kgms-2
                               =2.167 x 10-7 kgms-2




1.                      1.  What is 35 degrees Celsius in Fahrenheit?
  
                       Fahrenheit = 9 x 35°C / 5 + 32                   
                                   = 95 Fahrenheit


2.        What is 350 degrees Fahrenheit in Celsius?


 
        Use the formula C = 5/9 (F-32). 

350 degrees Fahrenheit = (350 - 32 ) x 5/9 = 176.67 degrees Celsius

3.       What is meant by normal freezing point?  

 

Normal freezing point is 0 degrees Celsius, 32 degrees Fahrenheit. Normal freezing point means the temperature at which a substance freezes, specifically at a pressure of 1 atmosphere.





Exercise 1
  S = ut + ½ (at2)
By using dimensional analysis, show that the equation is dimensionally correct.
Answer:
So, S = L

      S = (LT-1)(T) +  ½ (LT-2)(T)
      S = L + ½ L
      L = L + ½ L        =         both side with the same dimension
Hence, the equation is dimensionally correct

Exercise 2
show the homogenous of the physics equation below:
P=hpg where P is pressure, h is height, p is density and g is gravity. What is the unit of P??

h = height (m)                                SI Pascal = Pa
p = density (kgm-3)
g = gravity (Nkg-1)

P = hpg
MLT-2/L2 = (M/L3) (LT-1/T)
MT-2= L (M/L3) (LT-1/T)
MT-2 = M/L
M = M/L X (1/T2)
Thus, =MT-2/L






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