CBSE > Class 07 > Science | CBSE Board | Homework Help

Momentum is a quantity that can be calculated by multiplying the mass and velocity of the object involved. Momentum is expressed by the letter p. So momentum equals mass times velocity or p = m x v. Therefore, if any object of any mass is not moving, its momentum is zero because its velocity is zero.
Velocity is a measure of how quickly an object moves. So, the velocity is the change in the position of an object, divided by the time. Velocity has a magnitude (a value) and a direction. The unit for velocity is meters per second (m/s)
V = (X_f- X_i)/t = Δx/t

v = velocity (m/s)

x_f = the final position (m)

x_i = the initial position (m)

t = the time in which the change occurs (s)

Δx = short form for "the change in" position (m)

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How do we get silk from silkworm ?

Posted by Bhoomi Deswal 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 7 years, 1 month ago

In order to obtain silk, mulberry trees are cultivated, silkworms are reared and their cocoons are collected to get silk fibres. The various steps involved are:
(i) Rearing of silkworms: A female silk moth lays hundreds of eggs at a time. The eggs are stored by the farmers at suitable temperature and humidity under hygienic conditions. When the eggs hatch, silkworms come out of the eggs. The silkworms are fed mulberry leaves. After 25-30 days, the silkworms stop eating and get ready to spin cocoons. The silkworms enclose themselves completely inside the silken cocoons in two or three days.
(ii) Processing of cocoons to obtain silk fibres: The pile of cocoons is placed in hot water. Hot water makes the silk fibres of cocoons to separate out. The long fibres are obtained by unwinding the threads from cocoons. This process is called reeling.
(iii) Converting silk fibres into silk cloth: Silk fibres obtained from cocoons are spun (twisted) to form silk threads called silk yarn. The silk yarn is then woven on looms into silk cloth by the weavers.

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Explain why filament type electric bulbs are not power efficient. Name any two type of electric lighting devices which are much more energy efficient than filament type bulbs?

Posted by Rinku Biswas 7 years, 1 month ago

CBSE > Class 07 > Science

0 answers

ANSWER

What is eyes

Posted by Samiksha Goyal 7 years, 1 month ago

CBSE > Class 07 > Science

4 answers

Sarthak Jha 7 years, 1 month ago

Eyes are those organs which helps us to see. Moreover, it is one of the sense organs it consists of iris , lense. The disease related to eyes is called myopia.

2Thank You

Punj Bhootra 7 years, 1 month ago

The ability to see something

2Thank You

Sabibaa Bhanu 7 years, 1 month ago

The organ which is used to see

3Thank You

Samiksha Goyal 7 years, 1 month ago

The dvars is called eyes

2Thank You

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What percent of (rbc) haemoglobin present in adult human body???

Posted by Pranshu Gupta 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Shantanu Maurya 7 years, 1 month ago

12 to 14ml

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What is heart?

Posted by Yogesh Kumar 7 years, 1 month ago

CBSE > Class 07 > Science

2 answers

Gargi Pratinidhi 7 years, 1 month ago

Heart is an organ that beats or pumps continuously. It has four chambers. The two upper chambers are called atria and the lower are called ventricles. The heart does the work of purifing the blood and sending it to all parts of the body.

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Sabibaa Bhanu 7 years, 1 month ago

Heart is an organ which beats continuously to act as a pump to transport the blood ,whicg carries other substances with it.

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How is ground water recharged

Posted by Yuvraj Kumar 7 years, 1 month ago

CBSE > Class 07 > Science

4 answers

Harnoor Kaur 7 years, 1 month ago

Water from seas,rivers,oceans seepsinto the ground after rain.the process of seeping water into ground is known as infiltration. This is how the ground water recharged

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Rishi Raj 7 years, 1 month ago

It is recharge by rain water and also from we waste in bath etc.

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Vandna Singh? 7 years, 1 month ago

It is reacharched by rain water

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Sabibaa Bhanu 7 years, 1 month ago

It is recharged by rainwater harvesting

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The problem faced due to impoper management of sewage give 4 line ?

Posted by Prince Sidhu 7 years, 1 month ago

CBSE > Class 07 > Science

0 answers

ANSWER

What is a countination

Posted by Srishti Singh 7 years, 1 month ago

CBSE > Class 07 > Science

0 answers

ANSWER

What are the causes of soil erosion??

Posted by Monika Bansal 7 years, 1 month ago

CBSE > Class 07 > Science

0 answers

ANSWER

What is meant by plasma

Posted by Moushik Raja 7 years, 1 month ago

CBSE > Class 07 > Science

4 answers

Vijayalakshmi J 7 years, 1 month ago

Blood consists of two components- blood plasma and blood cells. Blood plasma is a colourless liquid with 90%water and 10%minerals.

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Vandna Singh? 7 years, 1 month ago

Plasma is a fluid substanceof a blood

1Thank You

Sabibaa Bhanu 7 years, 1 month ago

The fluid substance of the blood

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Adarsh Upadhyay 7 years, 1 month ago

the colourless liquid part of blood, in which the blood cells, etc. float is called plasma.

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What is erect image

Posted by Jattmakma Ji 7 years, 1 month ago

CBSE > Class 07 > Science

2 answers

Ankur Gupta 7 years, 1 month ago

The image which is formed upright in the mirror.

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Sabibaa Bhanu 7 years, 1 month ago

The image which is formed by convex mirror and concave lens

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tha fluid part of blood is called

Posted by Renitha R 7 years, 1 month ago

CBSE > Class 07 > Science

5 answers

Raghav Goel 7 years, 1 month ago

Plasma

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Hilal H 7 years, 1 month ago

The liquid part, called plasma, is made of water, salts, and protein. Over half of your blood is plasma. The solid part of your blood contains red blood cells, white blood cells, and platelets. Red blood cells (RBC) deliver oxygen from your lungs to your tissues and organs.

2Thank You

Vandna Singh? 7 years, 1 month ago

Plasma

2Thank You

Karan Kumar Naik 7 years, 1 month ago

Blood

1Thank You

Anjali Singh 7 years, 1 month ago

Rumination

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Properties of base and acid.

Posted by Naval Kishore Kandpal 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Naval Kishore Kandpal 7 years, 1 month ago

Acid - :- sour in taste :- soluble in water :- conduct electricity :- corresive in nature :- most react with matter to form hydrogen Base- :- bitter in taste :- sopy on touch :- some of them corresive in nature :- conduct electricity :- some can dissolve in water also called alkalis Thanks

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clone is

Posted by Deepanshu Veer 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Ramu Kumar 7 years, 1 month ago

Masal

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How are muscle cramps caused? How we can get relief from it?

Posted by Riddhima Agarwal 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Krisha Zala 7 years, 1 month ago

It is caused when oxygen is not flow through that muscle it cause our muscle to cramp

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ANSWER

Describe the function of heart in detail

Posted by Ashutosh Pathak 7 years, 1 month ago

CBSE > Class 07 > Science

2 answers

Sabibaa Bhanu 7 years, 1 month ago

Heart acts like a pump which transports the blood to all parts

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Anjali Singh 7 years, 1 month ago

Heart is our living organ.most of the person are dead by heart attak

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When two human does ***is done

Posted by Kartik Singhal 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Kartik Singhal 5 years, 9 months ago

Jab adami ghusa deta hai without condom aurat me ??

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Where is pollen in plant

Posted by Harsh Kumar 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Ashutosh Pathak 7 years, 1 month ago

In anther

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Differentiate between plants produced by sexual reproduction with those produced by the asexual reproduction?

Posted by Suraj Kadus 7 years, 1 month ago

CBSE > Class 07 > Science

0 answers

ANSWER

What is meant by mode

Posted by Harsheethaa Perumal 7 years, 1 month ago

CBSE > Class 07 > Science

1 answers

Yogita Ingle 7 years, 1 month ago

The mode is the value that appears most often in a set of data.
The mean is the total of all the values, divided by the number of values.
The median is the middle number in a list of numbers ordered from smallest to largest.

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What are artry

Posted by Imran Sheikh 7 years, 1 month ago

CBSE > Class 07 > Science

2 answers

Suchitra Sen 7 years, 1 month ago

It is thick tube like structure which carry oxyegenated blood from heart to different parts of body .

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Jashmeen Sahu 7 years, 1 month ago

The thick walled tube present under the skin is know as artery

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How many cells are there in pancreas and gallblader

Posted by Pranshu Gupta 7 years, 1 month ago

CBSE > Class 07 > Science

2 answers

Harini S 7 years, 1 month ago

Three million cells in pancreas

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Ishan Gupta 7 years, 1 month ago

pancreas has 5 types of cell.

1Thank You

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What are the components of blood

Posted by Chiranjeevi Singroul 7 years, 1 month ago

CBSE > Class 07 > Science

3 answers

Sabibaa Bhanu 7 years, 1 month ago

1.plasma 2.RBC 3.WBC 4.platelets

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Kandizzz . 7 years, 1 month ago

Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including: transporting oxygen and nutrients to the lungs and tissues.

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Harshit Kalra 7 years, 1 month ago

1. Plasma 2. Red Blood Cells (also called erythrocytes or RBCs) 3. White Blood Cells (also called leukocytes) 4. Platelets (also called thrombocytes)

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What are the difference between heart

Posted by Chiranjeevi Singroul 7 years, 1 month ago

CBSE > Class 07 > Science