Forces and Newton’s First Laws of motion: Class 11 CBSE Physics

Forces and Newton’s First Laws of motion: Class 11 CBSE Physics: Chapter 5 of class 11 physics is based on the dynamics of moving objects, dynamics deals with the cause and effects of moving objects, and chapter 5 of physics of class 11 is based on the laws of motion which is also known as Newtonian mechanics. The cause of motion is the force that is responsible to change the state of any object, so we will study in class 11 physics all types of noncontact forces like magnetic force, electrostatic force, gravitational force, and contact forces like tension, normal reaction, spring force, and friction, in this chapter, we will study tension, normal reaction, and gravitational force.

Forces and Newton’s First Laws of motion:Class 11 CBSE Physics

The types of forces: In mechanics there are three types of forces gravitational force, normal reaction and tension. In class 11 physics for solving the numerical questions every student requires to study all these forces to understand chapter 5-Laws of Motion.

Gravitational Force: The gravitational force is the force of attraction between two bodies in the universe.

Gravitational force or gravity of the earth on an object is the force which is the force of attraction exerted by the earth to any object and directed towards the centre of the earth.

According to Newton’s second law, the gravitation force on an object is the weight of the object, which is given as

F = mg(where  m is the mass of the object and g is gravitational acceleration)

The force on 1 kg  = 9.8 N and gravitational acceleration g = 9.8 m/s²

The gravitational force between two objects which are distant apart by d is given by

F = GmM/d²

If the object of the mass m is on the surface of the earth, then it is given by

F = GmM/r²(where r is the radius of the earth which is the distance between the object and the center of the earth)

Forces and Newton’s First Laws of motion: Class 11 Physics Chapter 5 CBSE

Normal Reaction:When two bodies are in contact to each other an upward force is applied by the surface of one body to the surface of another body which is perpendicular to the surface of the bodies ,normal reaction force(R) is the reaction of the gravitational force that keeps the body in balance.

Note: Normal reaction R is applied by the plane(one of the body) to the object(another body) is always equal to normal reaction applied by the object(one of the body) to the plane(another body).

Forces and Newton’s First Laws of motion:Class 11 Physics Chapter 5 CBSE

Tension:When an object is suspended on a plane by a rope, chain, or rod, in this case, two forces are applied to the object , one is the gravitational force and another force is applied opposite to the gravitational force along the rope known as tension(T). The plane in which the rope is connected also exerts the same tension force T in opposite to the later tension force T Since the string is the same.

Note: Here the mass of the string is supposed neglected

The force of tension is always shown directed away from the point of mass and in the case of the same string tension is the same.

Forces and Newton’s First Laws of motion: Class 11 Physics Chapter 5 CBSE

Free Body Diagram(F.B.D):In solving the numerical questions,free body diagram is used in which the following points are to be noted.

(i) All the objects even are of big masses supposed to be point masses and represented by a point.

(ii)All the forces should be shown acting on the object.

(iii)Forces are shown from a point of reference, the maximum time frame of reference is the ground which is also known as the inertial frame.

Example: The is an inclined plane in the form of a wedge, one end of a block is attached to its inclined plane and another end is attached to a vertical plane, if the system is in an equilibrium state then the forces of normal reactions are shown at the point of contact as bellow.

 

Forces and Newton’s First Laws of motion: Class 11 CBSE Physics

Newton’s First Law of Motion:If the net force on a body is zero then net acceleration on the body is zero,thus the state of the body will remain in its own position. If the body is in the stationary position it will remain in a static position or if a body is in motion then it will be carried on at the same constant velocity until and unless an external force is applied to it.

Let there are F₁,F_2, and F₃ forces are acting on an object and body is in equilibrium then net force F_net =0 and net acceleration a_net=0

Example: An object of mass 2 kg is suspended vertically downward through a string attached to a plane above the ground and another object of mass 5 kg is attached to the object of mass 2 kg through another string along the same downward direction then find the tension on both string if the system is in equilibrium?

Solution:

Showing the force of tension away of the object along the string as shown in the diagram

Two forces are applied on 5 kg object Tension T₁ and its weight 5g ,since it is in equilibrium

∴T₁= 5g = 5×9.8 =49 N

Three forces are applied on 2 kg object are tension,tension T_1, and its weight 2g ,since it is in equilibrium

∴ T = T₁ + 2g = 49 +2×9.8 =49+19.6 =68.6N

Therefore tension on both strings will be 49 N and 68.6 N.

You can also study class 11 Physics and Chemistry Notes

Circular Motion: Angular velocity and angular displacement

Projectile Motion Class 11 CBSE Physics Chapter 4 Motion in a Plane

Addition of Vectors: CBSE Class 11 Physics Chapter 4 -Motion in a Plane

Don’t forget to write a comment, subscribe us for the posts related to your study

Lattice Energy Class 11 CBSE Chemistry Chapter 4

Electronic Configuration of s,p and d orbitals

Atomic Radius Class 11 Chemistry Chapter 3 Periodicity in Properties

Why does a Rainbow look like a Bow?

NCERT Solutions of Science and Maths for Class 9,10,11 and 12

NCERT Solutions for class 9 maths

Chapter 1- Number System	Chapter 9-Areas of parallelogram and triangles
Chapter 2-Polynomial	Chapter 10-Circles
Chapter 3- Coordinate Geometry	Chapter 11-Construction
Chapter 4- Linear equations in two variables	Chapter 12-Heron’s Formula
Chapter 5- Introduction to Euclid’s Geometry	Chapter 13-Surface Areas and Volumes
Chapter 6-Lines and Angles	Chapter 14-Statistics
Chapter 7-Triangles	Chapter 15-Probability
Chapter 8- Quadrilateral

NCERT Solutions for class 9 science 

Chapter 1-Matter in our surroundings	Chapter 9- Force and laws of motion
Chapter 2-Is matter around us pure?	Chapter 10- Gravitation
Chapter3- Atoms and Molecules	Chapter 11- Work and Energy
Chapter 4-Structure of the Atom	Chapter 12- Sound
Chapter 5-Fundamental unit of life	Chapter 13-Why do we fall ill ?
Chapter 6- Tissues	Chapter 14- Natural Resources
Chapter 7- Diversity in living organism	Chapter 15-Improvement in food resources
Chapter 8- Motion	Last years question papers & sample papers

NCERT Solutions for class 10 maths

Chapter 1-Real number	Chapter 9-Some application of Trigonometry
Chapter 2-Polynomial	Chapter 10-Circles
Chapter 3-Linear equations	Chapter 11- Construction
Chapter 4- Quadratic equations	Chapter 12-Area related to circle
Chapter 5-Arithmetic Progression	Chapter 13-Surface areas and Volume
Chapter 6-Triangle	Chapter 14-Statistics
Chapter 7- Co-ordinate geometry	Chapter 15-Probability
Chapter 8-Trigonometry

Class 10 Maths Question Paper CBSE Half Yearly Exam 2022 With Solutions

CBSE Class 10-Question paper of maths 2021 with solutions

CBSE Class 10-Half yearly question paper of maths 2020 with solutions

CBSE Class 10 -Question paper of maths 2020 with solutions

CBSE Class 10-Question paper of maths 2019 with solutions

NCERT Solutions for Class 10 Science

Chapter 1- Chemical reactions and equations	Chapter 9- Heredity and Evolution
Chapter 2- Acid, Base and Salt	Chapter 10- Light reflection and refraction
Chapter 3- Metals and Non-Metals	Chapter 11- Human eye and colorful world
Chapter 4- Carbon and its Compounds	Chapter 12- Electricity
Chapter 5-Periodic classification of elements	Chapter 13-Magnetic effect of electric current
Chapter 6- Life Process	Chapter 14-Sources of Energy
Chapter 7-Control and Coordination	Chapter 15-Environment
Chapter 8- How do organisms reproduce?	Chapter 16-Management of Natural Resources

NCERT Solutions for class 11 maths

Chapter 1-Sets	Chapter 9-Sequences and Series
Chapter 2- Relations and functions	Chapter 10- Straight Lines
Chapter 3- Trigonometry	Chapter 11-Conic Sections
Chapter 4-Principle of mathematical induction	Chapter 12-Introduction to three Dimensional Geometry
Chapter 5-Complex numbers	Chapter 13- Limits and Derivatives
Chapter 6- Linear Inequalities	Chapter 14-Mathematical Reasoning
Chapter 7- Permutations and Combinations	Chapter 15- Statistics
Chapter 8- Binomial Theorem	Chapter 16- Probability

CBSE Class 11-Question paper of maths 2015

CBSE Class 11 – Second unit test of maths 2021 with solutions

NCERT Solutions for Class 11 Physics

Chapter 1- Physical World

chapter 3-Motion in a Straight Line

NCERT Solutions for Class 11 Chemistry

Chapter 1-Some basic concepts of chemistry

Chapter 2- Structure of Atom

NCERT Solutions for Class 11 Biology

Chapter 1 -Living World

NCERT solutions for class 12 maths

Chapter 1-Relations and Functions	Chapter 9-Differential Equations
Chapter 2-Inverse Trigonometric Functions	Chapter 10-Vector Algebra
Chapter 3-Matrices	Chapter 11 – Three Dimensional Geometry
Chapter 4-Determinants	Chapter 12-Linear Programming
Chapter 5- Continuity and Differentiability	Chapter 13-Probability
Chapter 6- Application of Derivation	CBSE Class 12- Question paper of maths 2021 with solutions
Chapter 7- Integrals
Chapter 8-Application of Integrals

Class 12 Solutions of Maths Latest Sample Paper Published by CBSE for 2021-22 Term 2

Class 12 Maths Important Questions-Application of Integrals

Class 12 Maths Important questions on Chapter 7 Integral with Solutions for term 2 CBSE Board 2021-22

Solutions of Class 12 Maths Question Paper of Preboard -2 Exam Term-2 CBSE Board 2021-22

Solutions of class 12  maths question paper 2021 preboard exam CBSE Solution