CBSE PHYSICS: Force Fiction and Pressure for VIII Physics-Notes a...

FORCE AND PRESSURE

A force is a push or pulls acting on an object which changes or tends to change the state of the object.

In the international system of units (SI System), the unit of force is Newton (N) that is named after Sir Isaac Newton.

There are also other units like dyne, kilogram weight and pound.

Action of force and its effects:

Contact and non-contact forces

A force forces which act only when there is physical contact between two interacting objects are known as contact forces.

Forces which can act without physical contact between objects, i.e. those that can act from a distance, are called non-contact forces or field forces.

Types of forces

1. Muscular force: This is the force we can exert with our bodies by using our muscles, e.g. pull, push, kick etc. These are contact forces

2. Magnetic force : Magnets exert forces of attraction or repulsion on other magnets. An important feature of magnetic force is that it can act from a distance, and is therefore of a non-contact force.

3. Electrostatic force: The force exerted by a charged body on another charged or uncharged body is known as electrostatic force. Electrostatic force is used to separate solid pollutant particles from smoke given out from factories.

4. Gravitational force : All objects in the universe exert a force on all other objects. This is called gravitational force. The gravitational force exerted by the Earth on all the bodies on its surface is called gravity.

5. Frictional force : The fact that the rolling ball comes to rest after some time shows that there must be a force acting on it which tends to slow it down. This force seems to be more on rough surfaces than on smooth surfaces. The force acting against the relative motion of surfaces in contact is called frictional force or friction.

6. Tension Force:Strings, ropes and chains can only pull on things! The force of pull supplied by strings, ropes or chains is called the tension force. The tension force is always directed along the length of the thing doing the pulling (string, rope, chain).

7. Spring Force‎: is the force exerted by a compressed or stretched spring upon any object that is attached to it.

8. Applied Force: An applied force is a force that is applied to an object by a person or another object. If a person is pushing a desk across the room, then there is an applied force acting upon the object. The applied force is the force exerted on the desk by the person.

Mass and Weight : The mass of an object is the amount of matter that is contained by the object; the weight of an object is the force of gravity acting upon that object.

The mass of an object (measured in kg) by Pan Balance and will be the same no matter where in the universe that object is located. On the other hand, the weight of an object (measured in Newton) by Spring balance and will vary according to where in the universe the object is

Type of friction:

CBSE PHYSICS: Fore Fiction and Pressure for VIII Physics-Notes Click Here

Comments

CBSE ADDA :By Jsunil Sir : Your Ultimate Destination for CBSE Exam Preparation and Academic Insights

Class 10 Chapter 02 Acid Bases and Salts NCERT Activity Explanation

NCERT Activity Chapter 02 Acid Bases and Salt Class 10 Chemistry Activity 2.1 Indicator Acid Base Red litmus No Change Blue Blue Litmus Red No change Phenolphthalein Colourless Pink Methyl Orange Pink Yellow Indictors are substance which change colour in acidic or basic media. Activity 2.2 There are some substances whose odour changes in in acidic or basic media. These are called olfactory indicators. Like onion vanilla, onion and clove. These changes smell in basic solution. Activity 2.3 Take about 5 mL of dilute sulphuric acid in a test tube and add few pieces of zinc granules to it. => You will observe bubbles of hydrogen gas on the surface of zinc granules. Zn + H2SO4 --> ZnSO4 + H2 => Pass the Hydrogen gas through the soap solution. Bubbles formed in the soap solution as Hydrogen gas it does not get dissolved in it

CBSE I NCERT 10th Numerical Problem solved Reflection and reflection of light

Q. 1. A concave mirror of focal length 20cm is placed 50 cm from a wall. How far from the wall an object be placed to form its real image on the wall? Solution: V= -50 cm F= -20cm From mirror formula 1/u = 1/f – 1/v = -1/20+ 1/50 = - 3/100 U = - 33.3 cm Therefore, the distance of the object from the wall x = 50 – u X = 50 – 33.3 = 16.7 cm. Q.2. An object is placed at a distance of 40cm from a concave mirror of focal length 15cm. If the object is displaced through a distance of 20 cm towards the mirror, By how much distance is the image displaced? Answer: Here f = - 15 cm, u = - 40 cm Now 1/f = 1/u + 1/v Then 1/v = 1/f – 1/u Or V= uf/u-f =( - 40 x -15)/25 = -24 cm Then object is displaced towards the mirror let u1 be the distance object from the Mirror in its new position. Then u1 = -(40-20) = -20cm If the image is formed at a distance u1 from the mirror then v1 = u1f/u1-f = -20X-15/-20+15 = -60 cm. = - 20 x-15/-20+15 = -60 cm. Therefor

Class 10 Metal and Non MetalsChapter 03 NCERT Activity Solutions

X Class 10 NCERT Activity Explanation Class 10 Metals and Non Metals Activity 3.1 Page No. 37 Take samples of iron, copper, aluminium and magnesium. Note the appearance of each sample. They have a shining surface. Clean the surface of each sample by rubbing them with sand paper and note their appearance again. They become more shiny. => Freshly cut Metal have shiny surface Activity 3.2 Page No. 37 Take small pieces of iron, copper, aluminium, and magnesium. Try to cut these metals with a sharp knife and note your observations. They are very hard to cut. Hold a piece of sodium metal with a pair of tongs and try to cut it with a knife. Sodium can be cut easily with knife. Hence K and Na are soft metal cut with knife Activity 3.3 Page No. 38 Take pieces of iron, zinc, lead and copper try to strike it four or five times with a hammer. These metals are beaten into thin sheet on hammering. This property of metal is called malleability and metals are called malleable. Activity 3.4 Page

Living science ratna sagar class 6 solutions

Ratna sagar living science 6 answers by jsunil. Class6 Living science solution Term-1 Living Science Solution chapter-1 Source of food Download File Living Science Solution chapter-2 Component of food Download File Living Science Solution chapter-3 Fibre to fabric Download File Living Science Sol ch-4 Sorting of material into group Download File Living Science Soln ch-5 Separation of substance Download File Living Science Solution chapter-6 Change around Us Download File Living Science Solution ch-7 Living and Non Living Download File Living Science Solution ch-8 Getting to Know Plants Download File Living Science Sol ch-9 The Body and Its movements Download File Visit given link for full answer Class6 Living science solution Term-II

Electricity numerical for class 10 CBSE Trend Setter 50 Problems

1. The current passing through a room heater has been halved. What will happen to the heat produced by it? 2. An electric iron of resistance 20 ohm draws a current of 5 amperes. Calculate the heat produced in 30 seconds. 3. An electric heater of resistance 8 ohm takes a current of 15 A from the mains supply line. Calculate the rate at which heat is developed in the heater. 4. A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply. Find the heat in joules produced by this combination in half a minute. 5. A resistance of 25 ohm is connected to a 12 V battery. Calculate the heat energy in joules generated per minute. 6. 100 joules of heat is produced per second in a 4 ohm resistor. What is the potential difference across the resistor? 7. An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at minimum heating’ it consumes a power of 360 W but at ‘maximum heating’ it takes a power of 840 W. Ca

CBSE ADDA

Search This Blog