Phylum porifera

PORIFERA

• 1, Water canal system_
  
  body wall encloses a cavity (spongocoel).water enters through pores (ostia) and goes out through an osculam , by the action of flagellated cells             (collar cells / choanocytes)

Why Bf3 's dipolemoment is zero?

         The dipolemoment of
         Bf3 become zero . why?

Because B-f bonds are oriented at an angle of 120° to each_other  , the three moment gives a net sum of zero . As a resultant of any two is equal and opposite to the third 

Theorem of parallel axis

Parallel_axis theorem 

The theorem states that,
            the moment of inertia of a body about any axis is equal to the sum of moment of inertia
   of a body about parallel axis ,passing through centre of mass. 
               And product of mass of the body and the square of the distance between the two axis

in this figure ,

According to parallelaxis theorem

Moment of inertia about 

AB= MI of CD + Ma*2

ie,       I= Icm + Ma*2

sample question , for competitive exams

A 60km foot_race was won with a time of about 4h and 40mins. Assuming constant speed,
What was the speed of the winner? ?..




Ans: 3.57 m/s

Animals, we can classify 11 Phyla

The kingdom Animalia we can classified into
               11 phyla (singular phylum)

* phylum- Porifera ( sponges)
* phylum- Coelenterata( gastro vascular cavitiad                                                                          animals)
* phylum- Ctenophora( sea walnuts)
* phylum- Platyhelminthes( flat worms)
* phylum- Ashelminthes(round worms)
* phylum- Annelida(segmented worms)
* phylum- Arthropoda(jointed leg animals)
* phylum- Molusca( soft boied animals)
* phylum- Echinodermata
* phylum- Hemichordata
* phylum- Chordata(modern)

jee main 2015 questions and answers. physics

    Jeemain 2015 ,questions and answers
            Part-1 Physics
                             

Man's taxonomical categories

         Man 's taxonomical categories

Common name : Man
Scientific name : Homo sapiens
Species name    : sapiens
            Genus     : Homo
             Family   : Hominidae
                Order  : primata
               Class    : Mamalia
            Phylum  : chordata
             Kindom: Animal kingdom(animalia)