This channel is content covering in various syllabi like CBSE, SSC, in various states of India, and in time, common core syllabi of major countries. We want to help teachers, parents, students and above all educational institutions to bring in quality by making the subjects very interesting and deeply enjoyable.
Showing posts sorted by date for query EXPERIMENTS WITH WATER. Sort by relevance Show all posts
Showing posts sorted by date for query EXPERIMENTS WITH WATER. Sort by relevance Show all posts
Wednesday, October 28, 2020
Monday, October 26, 2020
Sunday, October 25, 2020
Monday, October 12, 2020
Thursday, March 10, 2016
Saturday, March 5, 2016
EXPERIMENTS WITH WATER-TEXT
EXPERIMENTS WITH
WATER
ENVIRONMENTAL
STUDIES
CBSE-V
What
floats – what sinks?
Ayesha
was waiting for dinner. Today Ammi was making her favourite food – puri and
spicy potatoes. Ayesha watched as her mother rolled out the puri and put it in
the hot oil. She saw that at first the puri sank to the
bottom
of the pan.
As
it puffed up, the puri came up and started floating on the oil. One puri did
not puff up and did not float like the others. On seeing this, Ayesha took some
dough and rolled it into a ball. She flattened it and put it in
a
bowl of water. Alas! it sank to the
bottom and stayed there.
In
the evening Ayesha went for a bath. She had just come out when her mother
called, “Ayesha, you have dropped the soap in the water again.
Take
it out and put it in the soap case.” Ayesha was in a hurry and the soap case
fell out of her hands. It started floating on water. Ayesha
gently
put the soap in the soap case. She saw that the case continued to float, even
with the soap in it.
A
wooden boat in water will float. But a needle will sink! Why does this happen?
Let
me think... An iron ship will also float, though its’ much heavier
than
my boat!
Archimedes'
Principle of Buoyancy:
Archimedes'
principle indicates that the upward buoyant force that is
exerted on a body immersed in a fluid, whether fully or partially
submerged, is equal to the weight of the fluid that the body displaces.
Because
The reason that a ship floats is that it displaces a lot
of water. The displaced water wants to return to it's original
location, where the ship is now, and this pushes
the ship upwards. The force which pushes the ship up is called
the buoyancy force.
Archimedes
continued to do more experiments and came up with a buoyancy principle, that a
ship will float when the weight of the water it displaces equals the weight of
the ship and anything will float if it is shaped to displace its own weight of
water before it reaches the point where it will submerge.
This
is kind of a technical way of looking at it. A ship that is launched sinks into
the sea until the weight of the water it displaces is equal to its own weight.
As the ship is loaded, it sinks deeper, displacing more water, and so the
magnitude of the buoyant force continuously matches the weight of the ship and
its cargo.
But
a needle, light as a leaf, thin as a pin, will sink right in! Why does this
happen?
The
density of nail (as of iron) is much larger than the water.
So it sinks easily. The weight of the water displaced by
the ship is equal to its weight, so it floats. Whereas the
weight of the water displaced by the iron nail is less than
its weight so the iron nail sinks.
Have
you seen that some thing float on water while others sink? Think how this happens!
The poem here raises such questions.
Dead
Sea:
All
oceans and seas have salty water. The saltiest of all is the Dead Sea. How
salty? Imagine 300 grams of salt in one litre of water! Would you be able to
even taste such salty water? It would be very bitter.
Interestingly,
even if a person does not know how to swim, she would not drown in this sea.
She will float in water, as if lying down on it!
Remember
the lemon you floated in salty water?
What
dissolved, what did not?
On
Sunday Ayesha’s cousin brother Hamid came to her house
to
play. As soon as he came he asked his aunt to make his favourite shakkarpara (a
sweet dish).
Ammi
said, “Let me come back from the market, then I will make some for you. Why don’t
you help me? Take two glasses of water and put a bowl of sugar in it. Mix it
till it dissolves.” Hamid thought, “Let me
finish
this work fast. Then I will watch TV”.
Dandi
March:
This
incident took place in 1930, before India became independent. For many years
the British had made a law that did not allow people to make salt themselves.
They
had also put a heavy tax on salt. By this law people could not
make
salt even for use at home. “How can anybody live without salt?” Gandhiji said,
“How can a law not allow us to use freely what nature has given!” Gandhiji, with
several other people, went on a yatra (long walk) from Ahmedabad to the Dandi seashore
in Gujarat, to protest against
this
law.
Do
you know how salt is made? The sea water is collected in shallow beds dug in the
sand. Water is allowed to dry in the sun. After
the
water dries the salt remains on the ground.
THANKYOU,
NANDITHA
AKUNURI
FROM TASTING TO DIGESTING-TEXT
FROM TASTING TO
DIGESTING
ENVIRONMENTAL
STUDIES
CBSE-V
Different
tastes:
Taste
buds are sensory organs that are found on yourTONGUE and allow you to
experience tastes that are sweet, salty, sour, and bitter. How exactly do your
taste buds work? Well, stick out your tongue and look in the mirror.
Taste
buds contain the receptors for taste. They are located around the
small structures on the upper surface of the tongue, soft palate, upper
esophagus, the cheek, epiglottis, which are called papillae. The myth of the
tongue map; that 1 tastes bitter, 2 tastes sour, 3 tastes salt, and 4 tastes
sweet.
Jhumpa
ran into the kitchen and caught hold of her mother saying, “Ma, I am not going
to eat this bitter karela (bittergourd). Give me gur (jaggery) and roti.”
Ma smiled and said, “You ate roti and sugar in
the morning.” Jhoolan teased Jhumpa, “Don’t you get bored of only one kind of
taste?” Jhumpa replied quickly, “Do you get bored with licking imli
(tarmarind)? I bet your mouth is watering just by hearing the word imli.”
“Sure I love the sour imli. But I eat sweet
and salty things too. I even eat karela,” said Jhoolan and looked at her
mother.
They
both laughed heartily. Jhoolan said to Jhumpa, “Let’s play a game. You close
your eyes and open your mouth. I will put something to eat in your mouth. You
have to tell what it is.”
Jhoolan
took a few drops of lemon juice in a spoon and put them in Jhumpa’s mouth.
“Sour lemon,” Jhumpa replied quickly.
Jhoolan
then picked up a small piece of jaggery. Her mother suggested, “Crush it,
otherwise she will know what it is?” Jhoolan crushed the jaggery but Jhumpa
easily guessed it.
They
played the game with different food items. Jhumpa could tell the fried fish
even before tasting it. Jhoolan said, “Now close your nose, and tell me what
this is?” Jhumpa was confused, “It is a bit bitter, a little salty and somewhat
sour.
Give
me one more spoonful.” Jhoolan took another spoonful of the cooked karela,
uncovered Jhumpa’s eyes, and said, “Here it is, eat!” Jhumpa laughed, “Yes,
give me more.”
Nitu
was given a glucose drip:
Nitu
was very sick. All day she was vomiting and she also had loose motions.
Whatever she ate, she vomited. Her father gave her sugar and salt solution. By
evening Nitu was feeling weak and dizzy. When she got up to go to the doctor
she fainted.
Her
father had to carry her to the doctor. The doctor said that Nitu should get
admitted in the hospital. She needs to be given a glucose drip. Hearing this,
Nitu got confused. She knew that during the games period in school, the teacher
sometimes gave them glucose to drink.
But
what was a glucose drip? Doctor aunty explained, “Your stomach is
upset.
Your body is not keeping any food and water and it has become very weak. The
glucose drip will give you some strength quickly, even without eating.”
Story
– A Stomach with a Window:
In
the poem, you read about a soldier called Martin. In 1822, he was eighteen
years old and was very healthy. When he was shot, he got seriously hurt. At
that time Dr. Beaumont was called to treat him.
Dr.
Beaumont cleaned the wound and put the dressing. After one and a half years,
the doctor found that Martin’s wound had healed except for one thing.
He
had a big hole in his stomach. The hole was covered with a loose flap of skin,
like the washer in a football. Press the skin and you could peep into Martin’s
stomach! Not only that, the doctor could also take out food from the stomach by
putting a tube in the hole.
Dr.
Beaumont felt he had found a treasure. Can you guess how much time he spent on
doing different experiments on this stomach?
Nine
years! During this time Martin grew up and got married. At that time scientists
did not know how food was digested? How does the liquid (digestive juices) in
the stomach help? Does it only help in making the food wet and soft? Or does it
also help in digestion?
Dr.
Beaumont took some liquid (juices) out of the stomach. He wanted to see what
would happen to a food item kept in a glass filled with it. Would it get
digested on its own? For this he did an experiment. With the help of a tube, he
took out some digestive juice from the stomach.
At
8.30am he put twenty tiny pieces of boiled fish in 10 millilitres of the juice.
He kept the glass at the same temperature as that of our stomach – about 30°C.
When he checked at 2 pm he found that the pieces of fish had dissolved.
Dr.
Beaumont tried this experiment with different food items. He gave Martin the
same food at the same time and then compared how long it took for food to be
digested in the glass and in Martin’s stomach. He recorded his observations in
a table.
TABLE:
So,
what does our stomach do? Dr. Beaumont did many experiments and found out many
secrets about digestion. He found that food digests faster in the stomach than outside.
Did you notice this in the table?
Our
stomach churns the food to digest it. The doctor also saw that the food did not
digest properly when Martin was sad. He also found that the juice in our
stomach is acidic. Have you heard of anyone talking about acidity -especially
when that person has not eaten well or the food is not digested properly.
Dr.
Beaumont’s experiments became famous across the world. After this many
scientists did many such experiments. What did you say? No, they did not shoot
people in the stomach. Nor did they wait for a patient with a hole in the
stomach. They used other scientific ways to look inside our bodies.
Children Did you like the story of Martin or,
should we say, the story of our own stomach?
THANK
YOU,
NANDITHA
AKUNURI
Subscribe to:
Posts (Atom)