We often hear that objects appear to be weightless in a spaceship circling round the Earth. In order to examine the effect in some detail, let us first define, what do we mean by the weight? The real weight of an object is the gravitational pull of the Earth on the object.
The body is segmented. Each segment is attached to its neighbor by means of a modified portion of cuticle which is thin and flexible, they possess jointed appendages. These appendages have been modified for specialized functions.
The platyhelminthes are triploblastic acoelomates. There is development f a third layer, the mesoderm, which separates the ectoderm and endoderm. The playhelminthes exhibit bilateral symmetry, and body is unsegmented.
The law of conservation of angular momentum is one of the fundamental principles of physics. It has been verified from the cosmological to the submicroscopic level. The effect of the law of conservation of angular momentum is readily apparent if a single isolated spinning body alters its moment of inertia. This is illustrated by the diver in Fig. 5.13.
For example, in Obelia there are feeding individuals, the gastrozooids; the individuals capable of asexual reproduction only, the gonozooids, blastostyles and free-living or sexually reproducing individuals, the medusa…..
Cnidarians have double layer organization and are therefore diploblastic having tissue grade organization and have organs. During the development two germinal layers are formed the outer ectoderm and inner endoderm from which their bodies are constructed.
A particle is said to possess an angular momentum about a reference axis if it so moves that it’s angular position changes relative to that reference axis.
The angular momentum L of a particle of mass m moving with velocity v and momentum p (Fig. 5.10) relative to the origin O is defined as
These animals are composed of many cells however there is no tissue organization and have no organs. Sponges lack symmetry. In most sponges the body wall is formed of an outer layer, pinacoderm, made up of cells called pinacocytes:
Consider a mass m attached to the end of a massless rod as shown in Fig. 5.8.let us assume that the bearing at the pivot point O is frictionless. Let the system be in a horizontal plane. A force F is acting on the mass perpendicular to the rod and hence, this will accelerate the mass according to
Diploblastic animals belong to division radiata. The body of these animals consists of two layers of cells, ectoderm and endoderm. There is a jelly like mesenchyme or mesogloea which in most cases is non cellular. Diploblastic animals show lesser degree of specialization and they do not form specialized organs.
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Two Table are Design and Datasheet View
21 Jan, 2014
