Force and Pressure NCERT Science Class 8 Summary Note

Force 
The push or pull of an object, is called force. 

Forces are due to interaction between objects. 

Force applied on an object in the same direction add to each other. 

Force applied on an object in opposite directions substract each other. 

The strength of force is measured by its magnitude. 

A force can change the state of motion of an object. 
Change in state of motion jeans
Rest to motion
Motion to rest 
Increase in speed 
Decrease in speed

Force on an object may change its shape. 

Types of forces 
Contact force 
The force that can be applied only by touching object,is called contact force. 

Non-Contact force 
The force that can be applied without touching object,is called contact force. 

Muscular force 
The force resulting due to action of muscles is called muscular force. 

Friction
The force that oppose motion of an object. 

Magnetic force
The force exerted by a magnetic material is called magnetic force. 
Like pole repel each other. 
Unlike pole attract each other. 

Electrostatic force
The force exerted by a charged body , is called electrostatic force. 
Like charge repel each other. 
Unlike charge attract each other. 

Gravitational force 
The force of attraction between two objects, is called gravitational force. 

Gravity 
Force of attraction between any object and earth is called gravity. 

Pressure
The force acting on a unit area , is called pressure. 
Pressure= Force /Area 


Both gas and liquid exert pressure on wall of container. 

Atmosphere
The blanket of air around us is called atmosphere. 

Atmospheric pressure
The pressure exerted by air, is called atmospheric pressure. 




Comments

Post a Comment

Popular posts from this blog

Fibre to Fabric NCERT CBSE CLASS 7 Science Online Test/Quiz

Fibre to Fabric  NCERT CBSE Class 7 Online Test/Quiz for Fibre to Fabric  Online test for "fibre to fabric" consists of ten questions, all having four alternatives. You have to choose the correct option. After attempting all questions, enter your name, class, roll no and email id. Email id is asked because through that results will be share to you.  And at last don't forget to submit your answers. After submission you can see your results too.  Enjoy taking test.  Topic- Fibre to Fabric NCERT CBSE Science Class 7 Loading…
Read more

Light NCERT Science Class 8 Summary Note

Image
What Makes Things Visible   When light from an object enters our eyes, then we see the object.  The light may have been emitted or reflected by the object.  Mirror   Highly polished surface is called mirror.  Reflection Bending back of light ray after falling on a surface, is called reflection.  Incident ray The light ray which strikes any surface, is called incident ray.  Reflected ray  The ray that comes back from the surface after reflection, is called as reflected ray.  Normal Line perpendicular to surface at point of incidence of light ray, is called normal.  Angle of incidence The angle between normal and incident ray, is called angle of incidence.  Angle of reflection The angle between normal and reflected ray, is called angle of reflection.  Laws of reflection (i) The incident ray, the normal at the point of incidence and the reflected ray, all lie in the same plane.  (ii) The angle of incidence is always equal to the angle of reflection.  Nature of Images formed by Plane Mirro
Read more

Chemical Effects of Electric Current NCERT Summary Class VIII Science Chapter 14

Image
Good Conductor The substance through which electricity can pass is called good conductor.  Examples - Copper, Aluminum Poor conductor The substance through which electricity can not pass is called poor conductor. Examples - Rubber, plastic etc.  Tester A device that test conductance of a substance, is called tester.  Solutions of acids, bases and salts are generally good conductor.  Chemical effects of Current Chemical reactions (effects) caused when electricity passes through a conducting liquid, is chemical effects of current.  How to recognize chemical reaction - Release of gas - Change of colour of solution - Release of heat - Formation of new substance In battery No. of terminals- 2 (positive and negative)  Positive terminal is also called Anode .  Negative terminal is also called cathode .  Solution  is called electrolyte .  Passing current through a solution What happens when electricity is passed through c
Read more