Class 8 Exam > Class 8 Notes > Force And Pressure
Force And Pressure - Class 8 PDF Download
01
EXAMPLE
Push or Pull Forces
When you push against a wall the force that you exert is an example of a push force. When you pull a trolley car the force that you exert is an example of pull force.
02
FORMULA
Calculation of Pressure
For a force applied normally on an area , the pressure is given as
For example, for a force of applied on an area of , the pressure is
Note:
1. If force is not normal to the surface, only the components normal to the surface are considered.
2. For liquids, component of force on the surface is always normal to the surface.
For example, for a force of applied on an area of , the pressure is
Note:
1. If force is not normal to the surface, only the components normal to the surface are considered.
2. For liquids, component of force on the surface is always normal to the surface.
03
DEFINITION
Interactive nature of force
A force can be applied if the bodies which apply the force on each other interact. The interaction may or may not involve actual physical contact between the bodies but might actually interact from a distance. For example, like charges repel as the electric fields due to the two bodies interact.
04
EXAMPLE
Applications of pressure
Some applications of pressure are:
1. Sucking a drink with a straw.
2. Filling a syringe with a liquid.
3. Filling of ink in a fountain pen.
4. Action of rubber suckers.
1. Sucking a drink with a straw.
2. Filling a syringe with a liquid.
3. Filling of ink in a fountain pen.
4. Action of rubber suckers.
05
DEFINITION
Force and its unit
Force is a push or a pull acting on an object which changes or tends to change the state of the object.
For example:
Actions, like opening the door, lifting a bag, kicking a ball, pulling a drawer, pushing a box are some of the tasks we do every day. All these actions result in the change of position of an object and for that, it requires force in the form of push or pull.
S.I unit of force is newton () or .
For example:
Actions, like opening the door, lifting a bag, kicking a ball, pulling a drawer, pushing a box are some of the tasks we do every day. All these actions result in the change of position of an object and for that, it requires force in the form of push or pull.
S.I unit of force is newton () or .
06
EXAMPLE
Change of pressure and observe its effect
Take a rubber ball and make many holes in it with a needle. Fill the ball with water. Squeeze the ball with your hand. You will observed that water is coming with a great speed. Now slowly slowly if you decrease the applied pressure on the surface of the balloon, the speed of water will decrease. So more the pressure more forced induced towards the outside of the balloon.
As we know pressure = , so more the contact area lesser will be the pressure exerted by the molecules.
As we know pressure = , so more the contact area lesser will be the pressure exerted by the molecules.
07
EXAMPLE
Force changes direction of motion
When a ball hits against a wall, it bounces back in the opposite direction. So the force exerted by the wall on the ball changes its direction of motion.
08
EXAMPLE
Force changes shape of object
When a hammer strikes a hot rod, the rod bends. The force exerted by the hammer on the rod changes the shape of the rod.
09
EXAMPLE
Force can change the speed of an object
Blowing wind or wind storm can change the speed of moving car.
10
EXAMPLE
Force can change the direction of an object
A side wind can change the direction of a boat sailing in a sea.
11
EXAMPLE
Examples for effect of force
Force may bring the following change:
1) Can change the state of an object(rest to motion/ motion to rest):For example, pushing a heavy stone in order to move it.
2) May change the speed of an object if it is already moving.For example,catching a ball hit by a batsman.
3) May change the direction of motion of an object.For example,footballer kicks a moving ball to change its direction.
4) May bring about a change in the shape of an object.For example, blowing air in balloon.
5) May cause some or all of these effects.
1) Can change the state of an object(rest to motion/ motion to rest):For example, pushing a heavy stone in order to move it.
2) May change the speed of an object if it is already moving.For example,catching a ball hit by a batsman.
3) May change the direction of motion of an object.For example,footballer kicks a moving ball to change its direction.
4) May bring about a change in the shape of an object.For example, blowing air in balloon.
5) May cause some or all of these effects.
12
DEFINITION
Difference between Contact and Non-Contact force
| S.No. | Contact Force | Non-Contact Force |
| 1 | It acts when objects are in physical contact.Contact may be continuous or impulsive. | In acts when there is no physical contact in objects. |
| 2 | Muscular force,frictional force,spring force,normal force,tension force are few examples. | Gravitational force,electrostatic force,magnetic force and electrochemical force are few examples. |
13
EXAMPLE
Contact Forces
A force that can cause or change the motion of an object by touching it is called Contact Force.
For example, muscular force,frictional force,spring force,tension force,air resistance force etc.
For example, muscular force,frictional force,spring force,tension force,air resistance force etc.
14
DEFINITION
Muscular force and its examples
Muscular force is the force applied using parts of the body like arms or legs. It is force that results due to the action of muscles, and is a contact force.
All physical activity like running, lifting weight etc. requires muscular force.
All physical activity like running, lifting weight etc. requires muscular force.
15
DEFINITION
Tension Force
Tension force is the force transmitted through a string, rope, cable or wire when it is tightly pulled by forces acting from opposite ends.
Example: In the given figure, the string applies a tension force on the block.
Example: In the given figure, the string applies a tension force on the block.
16
EXAMPLE
Non-contact forces
A non-contact force is any force applied to an object by another body without any contact.
For example, magnetic force, gravitational force and electrostatic force.
For example, magnetic force, gravitational force and electrostatic force.
17
DEFINITION
Non-contact forces and their examples
A non-contact force is a force applied on an object by another body without being in direct contact with the object.
Examples:
Examples:
- Gravitational force
- Electromagnetic force
- Strong Nuclear force
- Weak Nuclear force
18
EXAMPLE
Magnetic force and its examples
Moving charges and current carrying conductors create magnetic fields. Also magnets themselves have magnetic fields. When you keep two magnets close together a force is exerted between them which is a magnetic force. Iron filings placed around a magnet move because a magnetic force acts on them.
19
DEFINITION
Electrostatic force
Electrostatic force is the force between two charged particles. It is more when the amount of charge on bodies is more and when distance between the charges is small.
Similar charges repel each other while opposite charges attract each other.
Similar charges repel each other while opposite charges attract each other.
20
DEFINITION
Define and explain the characteristics of electromagnetic force
The electromagnetic force is a special force that affects everything in the universe because (like gravity) it has an infinite range. It has the ability to attract and repel charges. The electromagnetic force can be generated by three types of fields known as the electrostatic field, magnetostatic field, and the electromagnetic field.
21
DEFINITION
Electromagnetic Force
Electromagnetic force is one of the four fundamental forces and exhibits electromagnetic fields such as magnetic fields, electric fields and light. It is the basic reason electrons bound to the nucleus and responsible for complete structure of nucleus.
It is the force exerted by the electromagnetic interaction of electrically charged or magnetically polarized particles or bodies.
Coulombs law: The force of attraction or repulsion between two charges is proportional to the product of magnitude of charges and inversely proportional to the square of distance between them acting along the line of joining the charges.
Lorentz Force: The fundamental force on an electric charge q moving with velocity v in a magnetic field B is called the magnetic Lorentz force.
22
DEFINITION
Characteristics of electromagnetic force
- These forces are both attractive as well as repulsive.
- They are central forces in nature.
- They obey the inverse square law.
- They are conservative forces in nature.
- These forces are due to the exchange of particles known as photons which carry no charge and have zero rest mass.
- They are times stronger as compared to gravitational forces.
23
DEFINITION
Pressure of liquid depends on gravitational force
The pressure of a liquid can be calculated by using a formula:
pressure of a liquid
height of the liquid column
density of the liquid
acceleration due to gravity
pressure of a liquid
height of the liquid column
density of the liquid
acceleration due to gravity
24
RESULT
Natural effects of atmospheric pressure
Some natural effects of atmospheric pressure are:
1. As the temperature in a region is increased, it creates a region of low pressure. This causes air to flow from high pressure regions to low pressure regions. Hence, winds are caused due to a difference in atmospheric pressure.
2. Atmospheric pressure decreases with increase in height. This creates harsher environments in higher altitudes. The combined effect of low temperatures and pressure at high altitudes is reflected by a reduction in the density of forests.
1. As the temperature in a region is increased, it creates a region of low pressure. This causes air to flow from high pressure regions to low pressure regions. Hence, winds are caused due to a difference in atmospheric pressure.
2. Atmospheric pressure decreases with increase in height. This creates harsher environments in higher altitudes. The combined effect of low temperatures and pressure at high altitudes is reflected by a reduction in the density of forests.
25
DEFINITION
Standard Atmospheric Pressure
Standard Atmosphere is mainly used as a reference value for the average atmospheric pressure at sea level. 1 standard atmosphere is defined as being exactly equal to 101,325 pascals.
Since the atmospheric pressure varies with changes in weather and altitude, it is convenient to standardise on a single value so that ratings, measurements and specifications can be compared. In particular 1 Standard Atmosphere is used by the Aviation industry as the reference standard for sea level pressure.
Since the atmospheric pressure varies with changes in weather and altitude, it is convenient to standardise on a single value so that ratings, measurements and specifications can be compared. In particular 1 Standard Atmosphere is used by the Aviation industry as the reference standard for sea level pressure.
26
EXAMPLE
Experimental demonstration of atmospheric pressureFill a cup one-third with water. Cover the entire mouth with an index card. Holding the card in place, turn the cup upside down. Remove your hand from underneath.Atmospheric pressure holds up the card and the water on it.
Thank u.!!
Related Exams
About this Document
|
4.81/5 Rating |
|
Nov 17, 2024 Last updated |
Document Description: Force And Pressure for Class 8 2024 is part of Class 8 preparation. The notes and questions for Force And Pressure have been prepared according to the Class 8 exam syllabus. Information about Force And Pressure covers topics like and Force And Pressure Example, for Class 8 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises and tests below for Force And Pressure.
Description
Full syllabus notes, lecture & questions for Force And Pressure - Class 8 - Class 8 | Plus excerises question with solution to help you revise complete syllabus | Best notes, free PDF download
Information about Force And Pressure
In this doc you can find the meaning of Force And Pressure defined & explained in the simplest way possible.
Besides explaining types of Force And Pressure theory,
EduRev gives you an ample number of questions to practice Force And Pressure tests, examples and also practice Class 8 tests.
Download as PDF
|
Explore Courses for Class 8 exam
|
|
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
Related Searches
Force And Pressure - Class 8
,Exam
,Force And Pressure - Class 8
,ppt
,Extra Questions
,Objective type Questions
,practice quizzes
,Free
,Sample Paper
,past year papers
,Semester Notes
,Previous Year Questions with Solutions
,study material
,Force And Pressure - Class 8
,Important questions
,Summary
,video lectures
,Viva Questions
,MCQs
,shortcuts and tricks
,mock tests for examination
;
Additional Information about Force And Pressure for Class 8 Preparation
Force And Pressure Free PDF Download
The Force And Pressure is an invaluable resource that delves deep into the core of the Class 8 exam.
These study notes are curated by experts and cover all the essential topics and concepts, making your preparation more efficient and effective.
With the help of these notes, you can grasp complex subjects quickly, revise important points easily,
and reinforce your understanding of key concepts. The study notes are presented in a concise and easy-to-understand manner,
allowing you to optimize your learning process. Whether you're looking for best-recommended books, sample papers, study material,
or toppers' notes, this PDF has got you covered. Download the Force And Pressure now and kickstart your journey towards success in the Class 8 exam.
Importance of Force And Pressure
The importance of Force And Pressure cannot be overstated, especially for Class 8 aspirants.
This document holds the key to success in the Class 8 exam.
It offers a detailed understanding of the concept, providing invaluable insights into the topic.
By knowing the concepts well in advance, students can plan their preparation effectively.
Utilize this indispensable guide for a well-rounded preparation and achieve your desired results.
Force And Pressure Notes
Force And Pressure Notes offer in-depth insights into the specific topic to help you master it with ease.
This comprehensive document covers all aspects related to Force And Pressure.
It includes detailed information about the exam syllabus, recommended books, and study materials for a well-rounded preparation.
Practice papers and question papers enable you to assess your progress effectively.
Additionally, the paper analysis provides valuable tips for tackling the exam strategically.
Access to Toppers' notes gives you an edge in understanding complex concepts.
Whether you're a beginner or aiming for advanced proficiency, Force And Pressure Notes on EduRev are your ultimate resource for success.
Force And Pressure Class 8 Questions
The "Force And Pressure Class 8 Questions" guide is a valuable resource for all aspiring students preparing for the
Class 8 exam. It focuses on providing a wide range of practice questions to help students gauge
their understanding of the exam topics. These questions cover the entire syllabus, ensuring comprehensive preparation.
The guide includes previous years' question papers for students to familiarize themselves with the exam's format and difficulty level.
Additionally, it offers subject-specific question banks, allowing students to focus on weak areas and improve their performance.
Study Force And Pressure on the App
Students of Class 8 can study Force And Pressure alongwith tests & analysis from the EduRev app,
which will help them while preparing for their exam. Apart from the Force And Pressure,
students can also utilize the EduRev App for other study materials such as previous year question papers, syllabus, important questions, etc.
The EduRev App will make your learning easier as you can access it from anywhere you want.
The content of Force And Pressure is prepared as per the latest Class 8 syllabus.
|
© EduRev
|
Education Revolution
|
Follow Us
|
Signup to see your scores
go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup