Thursday 26 December 2013

Movement of Animals

Without the ability to move, there would be no life on Earth. Moving around is

essential to many animals for finding food and a mate. Even plants move, by

spreading themselves with the help of seeds or sprouts. But how is moving around

possible? What kinds of adaptations
do different kinds of animals in different environments have, and how do they help

them survive? Lets take a look at that.

Movement in Earthworm :

An earthworm move by contracting its muscles to shorten its body, then extending

the body to reach further. When an earthworm contracts its body, it holds shortened

portion or base to the ground with small bristles. These bristles anchor the worm,

allowing it to not slip backward when contracting and allowing it to stretch.

Earthworms are also covered in mucus, which helps their movement through soil.

Earthworms are highly beneficial to the soil as their movement mixes the dirt they

travel through. Worms also aid in the breakdown of organic matter such as

vegetation by consuming it. Earthworms tend to feed on leaves, plants and even clay

and chalk. Earthworm movement also creates open paths in the dirt, which allow for

water flow and water removal.

Movement in Snail :

The snail has an unusual body sticking out from the underside of its coiled shell.

This body is actually a strong muscle called a foot. A snail’s foot is made up of

many tiny muscles which help it to crawl about in an up-and-down, or wavelike,

motion. The waves start at the front of the snail’s foot and move backwards. As the

waves pass through the muscles from one end of the foot to the other, the snail

glides forward.

Snails can creep on the ground or on the ocean floor, climb walls and trees, and

even hang upside down. This is because as the snail moves, a sticky fluid, called

mucus, flows out from tiny glands in front of the foot. The mucus acts as a track

or roadway, allowing the snail to stick to surfaces, even while hanging upside

down. This mucus also protects the snail from rough or sharp surfaces. A snail can

actually glide right over the sharp edge of a knife or razor blade without getting


Snails can creep completely into their shell and even seal themselves in with a

“door” of their dried mucus!

Movement in Fish :

Fish swim by propelling themselves through the water in a wave-like fashion. Fish

with streamlined bodies and crescent-shaped caudel fins move faster through the

water by moving their tail from side to side - this moves them forward a lot like

rowing a boat with an oar.

Fish also use their pectoral fins, which are situated horizontally on the body of

fish who are fast swimmers. In combination with the pelvic fins, these help to

stabilize the fish to keep it from rolling over as it moves through the water.

The pectoral fins are set almost vertically in slower swimming fish. These with the

pelvic fins help the fish by acting as brakes. They can also assist the fish with

difficult maneuvers. Take an hour to just watch your fish swimming and you will

understand how they swim and why and you will start to see which kinds of aquariums

are more conducive to a better and healthier way of life for your fish. In general,

because of the way fish are put together (their anatomy) you can see that they

generally swim horizontally. This is why a longer, rectangular aquarium is best to

allow them to swim and maneuver freely.

Movement in Birds :

Birds are adapted to moving in the air. Their front limbs have turned into wings

and their strong pectoral muscles move their feathered wings. Bird bones are hollow

inside so that the bodyweight is as small as possible, which makes it easier for

them to fly.

Wing movement provides lift as well as the propulsion needed to overcome "drag" and

to gain speed. The bird's wing movement might be compared to a swimmer's doing the

"butterfly stroke." His arms rotate around his shoulder joint, as he throws them

forward through the air and then pulls them back through the water. Flight,

however, is far more complex, involving the rotation of the wing and the relative

movements of various parts of it.

The faster the bird travels, the more lift will come from the air passing around

the wings. It has been calculated that a pigeon first taking off uses five times as

much energy as when it reaches steady flight.

With most larger birds, the increased wingspan is still not large enough to cope

with their extra weight and greater drag, especially when taking off. So some of

these, such as the pelican, run on the ground for a few feet to gain speed for

lift. Others, such as the vultures, land on a tree or fence and then, by jumping

off, gain enough speed through the pull of gravity for their wings to provide lift.

The heaviest bird that can fly is the trumpeter swan, weighing up to 40 pounds (18

kilograms). Heavy birds are limited in the amount of flapping they can do because

of the strenuous effort involved. However, this does not restrict their ability to

fly, for they are masters of another form of flight.

Movement in Snakes :

Snakes have four ways of moving around.  Since they don't have legs they use their

muscles and their scales to do the "walking".

- Serpentine method:  This motion is what most people think of when they think of

snakes. Snakes will push off of any bump or other surface, rocks, trees, etc., to

get going. They move in a wavy motion. They would not be able to move over slick

surfaces like glass at all. This movement is also known as lateral undulation.

- Concertina method:  This is a more difficult way for the snake to move but is

effective in tight spaces.  The snake braces the back portion of their body while

pushing and extending the front portion.  Then the snake drops the front portion of

their body and straightens an pulls the back portion along.  It is almost like they

through themselves forward.

- Sidewinding: This is a difficult motion to describe but it is often used by

snakes to move on loose or slippery surfaces like sand or mud.  The snake appears

to throw its head forward and the rest of its body follows while the head is thrown

forward again.  (See picture.)

- Rectilinear Method:  This is a slow, creeping, straight movement.  The snake uses

some of the wide scales on its belly to grip the ground while pushing forward with

the others.

Movement in Human Beings :

The skeleton is the inner framework of BONES that supports and gives shape to the

human body. It also protects some of the soft organs of the body—for example, the

skull surrounds the brain. Muscles and ligaments pull on the bones of the skeleton

at JOINTS to make the body move.

Weight for weight, bone is five times stronger than steel, but it is very light.

The skeleton makes up only one-sixth of an adult’s weight. The skull, in

particular, is very strong, because it has to protect the brain and sense organs,

such as the eyes, ears, and nose.

This strong yet flexible material is a living tissue, made up of bone cells

embedded in a matrix of fibers. Bone is not solid—blood vessels and nerves run

through tunnels within it, and some areas are a honeycomb of small spaces. In the

center of many bones is a cavity packed with a jellylike substance called bone


The hard matrix of bone is made of crystals of calcium phosphate and other

minerals, and fibers of protein called collagen. The minerals make bone hard, while

the collagen fibers are arranged lengthwise to make bone flexible. Both are

produced by cells called osteocytes, found throughout the matrix.

Bones connect at joints. Different types of joint allow different movements. Joints

are often held together by straps of tough fibrous tissue, called ligaments, and

the muscles that cross the joint. The four major movable joints in our body are :

1. Hinge Joints
The human skeleton's range of movements depends on its joints--literally where

bones join with each other. One of the more obvious of such joints is the hinge

joint, of which is expressed every time we flex our elbows or knees.

2. Ball and Socket
There are four primary ball and socket joints in the human body, at both shoulders

and both hips. They allow the widest range of motion in the human body, offering

lateral, vertical and rotational movement across a much wider range than any other

individual joint.

3. Glide Joints
Glide joints allow the sliding of bone over each other. These are primarily found

in the hands and feet of the skeleton, and while are limited in range of motion,

offer overall flexibility across a surface.

4. Pivot Joint
Pivot joints allow rotation along an axis, such as that which is utilized by our

skull and spine. The two bones of the forearm also utilize a pivoting motion, but

rotate around each other.

- Overall Movement
The simplest actions, such as picking up an apple and bringing it to your mouth, is

actually a complex orchestra of multiple joints working in tandem. Even grasping

the apple utilizes the full range of hinge and gliding joints found in your hand.

YashRaj Kandya
Student of Class 6
National Public School Indore 452005

Monday 16 December 2013

Electricity And Circuits

Electricity needs a path to pass from the positive terminal to the negative terminal of an electric cell.   A connection that provides a path outside an electric cell, for the electricity to pass from the positive terminal to the negative terminal of the cell, is called an electrical circuit.    

For example, a bulb glows only when the positive terminal and the negative terminal of an electric cell are connected to the two terminals of the bulb.

If the wires from the bulb are connected to the same terminal (either positive or negative), then the bulb doesn’t glow.

Sometimes, the bulb may not glow even though the connections are properly made.

This is because the flow of electricity is incomplete as the filament in the bulb is broken. A broken filament bulb is said to be fused.

A device that is used to stop the flow of electricity by breaking the circuit is called a switch. Switches have wide range of applications. Some common types are:

Toggle switches, which are used in our houses.

Pushbutton switches, which are used in the starter of a water pump.

Joystick switches, which are used in the remote control unit of a toy car.

For Questions 1 to 10 visit link : Class VI Physics 
YashRaj Kandya

11. What conductors and insulators?

Ans: The materials which allow electric current to pass through them are called conductors. Examples: All metals like Copper,Iron, Silver and Human body.
INSULATORS: The materials which do not allow electric current to pass through them are called bad conductors or insulators. Examples: Plastic, Wood, Rubber and Glass.

12. Why do electricians wear rubber gloves and shoes while at work?

Ans: It because rubber gloves are an insulator and prevent current to flow in body .Thus saves electricians from electric shock.

13. What do you mean by heating effect of current?

Ans: Electric current is actually the flow of electrons in the conducting material. Now,
when these electrons flow, they encounter some resistance in the structure of the conductor, which accounts for the "resistance" of materials. As the electrons collide or vibrate, heat energy is generated depending on the resistance of the conductor. This overall effect is called heating effect of electrical current.

14. Name a few appliances that work on the heating effect of current?

Ans: Electric kettle: Used for boiling water to make tea or coffee
Electric bulb : The filament of the bulb is heated when current flows and becomes white hot to emit brilliant light.
Electric iron: Used for ironing or pressing clothes.  
Electric toaster: Used to toast bread

15. Name a special material used for Heating Component?

Ans: It is a coil of wire made of a special material called nichrome which becomes very hot when current is passed. This heat is used to cook food (as in an electric stove), heat water ( as in an electric kettle, electric heater) etc

16. Name the elements used to make an alloy nichrome?

Ans: Nickel and Chromium.

17 Why are electric wire are made up of copper through silver is best conductor?

Ans: Silver is an expensive metal. Material needed for conductor should be cheap as wires are used extensively in almost every appliance. That is why silver can't be used to make wires.

18. Why do you apply a tap over the joint of electric wire?

Ans: Tap is an insulator and save us from electric shock.

19. If you connect a battery cell to the bulb through a wooden stick, the will not glow. Why?

Ans: No, wooden stick is an insulator that cannot conduct electricity

20. Do not handle the electric appliances when your hands are wet. Why?

Ans: Tap water is good conductor and we may get electric shock.

21. There will be three colored wires normally used while connecting any electric equipment. What are those colors? Tell which coloured wire gives us electric shock?

Ans: Red (Live wire that give us electric shock), Black (Neutral) , and Green(Earth wire)

Electricity and Circuits for Class 6
Electricity Circuits and Conductors
Electric Circuits KS2
Electric Circuits Info
Electrical Circuits Games
Interactive Circuits
BBC Electricity Circuits
Science Circuit
Hyper Staffs Electric Circuits

Electricity Circuits and Conductors
Electric Circuits KS2
Electric Circuits Info
Electrical Circuits Games
Interactive Circuits
BBC Electricity Circuits
Science Circuit
Hyper Staffs Electric Circuits

YashRaj Kandya
Student of Class 6
National Public School Indore 452005

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