# 8TH STANDARD SCIENCE BOOK

 Author: ANNETTA SCOTLAND Language: English, Indonesian, Japanese Country: Kyrgyzstan Genre: Academic & Education Pages: 183 Published (Last): 14.01.2016 ISBN: 244-9-24099-512-1 ePub File Size: 28.45 MB PDF File Size: 9.32 MB Distribution: Free* [*Registration Required] Downloads: 49415 Uploaded by: RHODA

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## Standards-Aligned Science Programs

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Hi Bala Sankar, We now made an update in 8th social book link.

Hi Ramyarao, Thanks for your comment. Will check and update you as soon as possible. Image on the right shows an activity demonstrating pull action pulling the rope.

And image on the left shows an activity demonstrating a push action pushing the ground so as to lift the body. Force: Occurs due to Interaction At least two objects must interact for a force to play a role. Interaction between the objects can be physical or non-physical.

Ex of Physical Interaction: pulling a rope, hitting a ball with bat, etc. Ex of non-Physical interaction: Magnetic force, electrostatic force, gravitational force, etc. We are going to discuss them in detail as we move ahead in this chapter.

Strength of a force is expressed by its magnitude. But to completely determine a force we need to specify both direction and magnitude as if the direction or magnitude of the applied force changes its effect changes. Example: Consider a Box kept on a horizontal ground.

Figure A below depicts that the force might move the box if it is of proper magnitude. But in case of figure B below , no matter how much force you apply the box is never going to move. So the net force in this case will be the summation of the forces.

## NCERT Class VIII ScienceText Book

While In case, Forces are applied on an object in opposite direction, then the net force will be difference of both the forces. Effects of Force Change in State of motion State of motion of is described by direction of motion and speed of the object. Even if the speed of object is zero it is to be considered in state of motion which is referred to as state of rest.

State of motion of an object cannot change until and unless some force acts on the object.

Example of increase in speed: Consider the image beside; as the player kicks the ball the changes its speed from zero to a non-zero value thus changing the state of motion of the ball. Similar situation can be thought when a player kicks a moving ball in the game increasing the speed of moving object Example of decrease in speed: The image in the side shows that as the dog catches the ball its speed comes down from a non-zero value to a zero value, which finally results in change of state of motion of the ball It is clear from the image besides that as the person hits the ball from the bat the direction of motion of ball changes thus changing the direction of motion of the ball Does a force always result in motion?

No, force always need not change the direction of motion. For example: pushing a wall will not result is change of its motion, etc Conclusion: It might be concluded that whenever the direction of force is in the direction of motion than the speed of object increases and whenever it is opposite to the direction of motion it speed decreases.

And force always need not change state of motion. Change in shape of an object Example 1: As clear from the image when a force is applied to a fixed spring in the direction of arrow then the spring gets extended thus changing its shape Simillarly the spring gets compressed if the direction of force was opposite to the direction applied in above picture.

Example2: A very common observation that when we try to pull rubber band, it gets elongated. Types of Forces Contact Forces Muscular Forces: Muscles functions to produce a force which is known as muscular force.

It acts during the basic day to day work of our life such as breathing, digestion, lifting a bucket, pulling or pushing some object. Since Muscular force can be applied on objects only when it is in contact with the object, it comes under contact force category Push-up-with-feet-on-an-exercise-ballThe sessions are conducted by some of the best Science teachers across the country. Noise pollution, its causes, impacts and control measure are explained towards the finish of the chapter.

Life iScience Program Overview Glencoe iScience meets students where they are through engaging features and thought-provoking questions that encourage them to relate the science concepts to the world around them.

Do fluids additionally direct power? It will push them to build up a hold of the subject as well as ace the ideas that will assist them with performing better.

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## NEW! Professional Learning Opportunities

Once you have mastered the way to comprehend 8th class science, then you should not leave any stone unturned. Chapter 8 - Cell - Structure and Functions Chapter 8, Cell — Structure and Functions explains the inside and out information about the major unit of life — cell. Where do Microorganisms Live?