Force is equal to the rate of change of momentum. For a constant mass, force equals mass times acceleration.
Sir Issac newton
Defining Newton’s Second Law of Motion
Newton’s second law states that the acceleration of an object depends upon two variables – the net force acting on the object and the mass of the object. The acceleration of the body is directly proportional to the net force acting on the body and inversely proportional to the mass of the body. This means that as the force acting upon an object is increased, the acceleration of the object is increased. Likewise, as the mass of an object is increased, the acceleration of the object is decreased.
Newton’s second law can be formally stated as,
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
The above equation can be rearranged to a familiar form as
\(\begin{array}{l}F=ma\end{array} \)
Since force is a vector, Newton’s second law can be written as
\(\begin{array}{l}\vec{F}=m\vec{a}\end{array} \)
The equation shows that the direction of the total acceleration vector points in the same direction as the net force vector.
Deriving Newton’s Second Law
For Changing Mass
Let us assume that we have a car at a point (0) defined by location X0 and time t0. The car has a mass m0 and travels with a velocity v0. After being subjected to a force F, the car moves to point 1 which is defined by location X1 and time t1. The mass and velocity of the car change during the travel to values m1 and v1. Newton’s second law helps us determine the new values of m1 and v1 if we know the value of the acting force.
Taking the difference between point 1 and point 0, we get an equation for the force acting on the car as follows:
Let us assume the mass to be constant. This assumption is good for a car because the only change in mass would be the fuel burned between point “1” and point “0”. The weight of the fuel is probably small relative to the rest of the car, especially if we only look at small changes in time. Meanwhile, if we were discussing the flight of a bottle rocket, then the mass does not remain constant, and we can only look at changes in momentum.
For Constant Mass
For a constant mass, Newton’s second law can be equated as follows:
We know that acceleration is defined as the change in velocity divided by the change in time. The second law then reduces to a more familiar form as follows:
\(\begin{array}{l}F=ma\end{array} \)
The above equation tells us that an object will accelerate if it is subjected to an external force. The amount of force is directly proportional to the acceleration and inversely proportional to the object’s mass.
What is a Net Force?
A net force ΣF is the sum of all forces acting on a body. More precisely, it is the vector sum of all forces acting on a body. Consider two forces of magnitude 30 N and 20 N that are exerted to the right and left, respectively on the horse shown in the above picture. If we assume the rightward direction as positive, then the net force on the horse can be calculated as follows: \(\begin{array}{l}\sum F=30\,N-20\,N=10\,N\end{array} \) \(\begin{array}{l}\sum F=10\,N\,to \,the\, right\end{array} \)
Application of Second Law
Newton’s second law is applied to identify the amount of force needed to make an object move or make it stop. Following are a few examples that we have listed to help you understand this point:
Kicking a ball
When we kick a ball, we exert force in a specific direction. The stronger the ball is kicked, the stronger the force we put on it and the further away it will travel.
Pushing a cart
It is easier to push an empty cart in a supermarket than a loaded one, and more mass requires more acceleration.
Two people walking
Among the two people walking, if one is heavier than the other, the one weighing heavier will walk slower because the acceleration of the person weighing lighter is greater.
Newton’s Second Law Solved Examples
Example 1:
If there is a block of mass 2kg, and a force of 20 N is acting on it in the positive x-direction, and a force of 30 N in the negative x-direction, then what would be its acceleration?
We first have to calculate the net force acting on it to calculate its acceleration.
\(\begin{array}{l}F_{net} = 20 N – 30 N = -10 N\end{array} \)
The negative acceleration indicates that the block is slowing and its acceleration vector is moving in an opposite direction directed opposite to the direction of motion.
Example 2:
How much horizontal net force is required to accelerate a 1000 kg car at 4 m/s2? Solution: Newton’s 2nd Law relates an object’s mass, the net force on it, and its acceleration: Therefore, we can find the force as follows: Fnet = ma Substituting the values, we get 1000 kg × 4 m/s2 = 4000 N Therefore, the horizontal net force is required to accelerate a 1000 kg car at 4 m/s-2 is 4000 N.
Newton’s second law is applied in daily life to a great extent. For instance, in Formula One racing, the engineers try to keep the mass of cars as low as possible. Low mass will imply more acceleration, and the more the acceleration, the chances to win the race are higher.
Frequently Asked Questions – FAQs
Q1
How does Newton’s second law of motion apply to rockets?
According to Newton’s second law of motion, we know that force is a product of mass and acceleration. When a force is applied to the rocket, the force is termed as thrust. The greater the thrust, the greater will be the acceleration. Acceleration is also dependent on the rocket’s mass, and the lighter the rocket faster is the acceleration.
Q2
How does Newton’s second law apply to a car crash?
According to the definition of Newton’s second law of motion, force is the dot product of mass and acceleration. The force in a car crash is dependent either on the mass or the acceleration of the car. As the acceleration or mass of the car increases, the force with which a car crash takes place will also increase.
Q3
What is the other name for Newton’s second law?
The other name for Newton’s second law is the law of force and acceleration.
Q4
What are some daily life examples of Newton’s second law of motion?
Newton’s second law of motion explains how force can change the acceleration of the object and how the acceleration and mass of the same object are related. Therefore, in daily life, if there is any change in the object’s acceleration due to the applied force, they are examples of Newton’s second law.
Acceleration of the rocket is due to the force applied, known as thrust, and is an example of Newton’s second law of motion.
Another example of Newton’s second law is when an object falls from a certain height, the acceleration increases because of the gravitational force.
Q5
Write the formula for Newton’s second law of motion?
The formula for Newton’s second law of motion is F=ma.
Q6
State Newton’s second law of motion
Newton’s second law of motion states that “Force is equal to the rate of change of momentum. For a constant mass, force equals mass times acceleration.
Q7
For a constant mass, how is Newton’s second law equated?
For a constant mass, Newton’s second law can be equated as:
A net force ΣF is the sum of all forces acting on a body.
Neeraj Anand, Param Anand
Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations.
In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS".
He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.
Below we have provided the details of the CBSE Physics topics under each unit as per the revised CBSE Class 11 Physics Syllabus for the 2023-24 academic year. Go through it to get the details of the chapters given below.
Unit-I: Physical World and Measurement
Chapter 2: Units and Measurements
Need for measurement: Units of measurement; systems of units; SI units, fundamental and derived units. Length, mass and time measurements; accuracy and precision of measuring instruments; errors in measurement; significant figures.
Dimensions of physical quantities, dimensional analysis and its applications.
Unit-II: Kinematics
Chapter 3: Motion in a Straight Line
Frame of reference, Motion in a straight line, Elementary concepts of differentiation and integration for describing motion, uniform and nonuniform motion, and instantaneous velocity, uniformly accelerated motion, velocity-time and position-time graphs. Relations for uniformly accelerated motion (graphical treatment).
Chapter 4: Motion in a Plane
Scalar and vector quantities; position and displacement vectors, general vectors and their notations; equality of vectors, multiplication of vectors by a real number; addition and subtraction of vectors, relative velocity, Unit vector; resolution of a vector in a plane, rectangular components, Scalar and Vector product of vectors.
Motion in a plane, cases of uniform velocity and uniform acceleration-projectile motion, uniform circular motion.
Unit-III: Laws of Motion
Chapter 5: Laws of Motion
Intuitive concept of force, Inertia, Newton’s first law of motion; momentum and Newton’s second law of motion; impulse; Newton’s third law of motion (recapitulation only). Law of conservation of linear momentum and its applications. Equilibrium of concurrent forces, Static and kinetic friction, laws of friction, rolling friction, lubrication.
Dynamics of uniform circular motion: Centripetal force, examples of circular motion (vehicle on a level circular road, vehicle on a banked road).
Unit-IV: Work, Energy and Power
Chapter 6: Work, Energy and Power
Work done by a constant force and a variable force; kinetic energy, work-energy theorem, power.
Notion of potential energy, potential energy of a spring, conservative forces: conservation of mechanical energy (kinetic and potential energies); non-conservative forces: motion in a vertical circle; elastic and inelastic collisions in one and two dimensions.
Unit-V: Motion of System of Particles and Rigid Body
Chapter 7: System of Particles and Rotational Motion
Centre of mass of a two-particle system, momentum conservation and centre of mass motion. Centre of mass of a rigid body; centre of mass of a uniform rod. Moment of a force, torque, angular momentum, law of conservation of angular momentum and its applications.
Equilibrium of rigid bodies, rigid body rotation and equations of rotational motion, comparison of linear and rotational motions.
Moment of inertia, radius of gyration, values of moments of inertia for simple geometrical objects (no derivation).
Unit-VI: Gravitation
Chapter 8: Gravitation
Kepler’s laws of planetary motion, universal law of gravitation. Acceleration due to gravity and its variation with altitude and depth. Gravitational potential energy and gravitational potential, escape speed, orbital velocity of a satellite.
Unit-VII: Properties of Bulk Matter
Chapter 9: Mechanical Properties of Solids
Elasticity, Stress-strain relationship, Hooke’s law, Young’s modulus, bulk modulus, shear modulus of rigidity (qualitative idea only), Poisson’s ratio; elastic energy.
Chapter 10: Mechanical Properties of Fluids
Pressure due to a fluid column; Pascal’s law and its applications (hydraulic lift and hydraulic brakes), effect of gravity on fluid pressure.
Viscosity, Stokes’ law, terminal velocity, streamline and turbulent flow, critical velocity, Bernoulli’s theorem and its applications.
Surface energy and surface tension, angle of contact, excess of pressure across a curved surface, application of surface tension ideas to drops, bubbles and capillary rise.
Chapter 11: Thermal Properties of Matter
Heat, temperature,( recapitulation only) thermal expansion; thermal expansion of solids, liquids and gases, anomalous expansion of water; specific heat capacity; Cp, Cv – calorimetry; change of state – latent heat capacity.
Heat transfer-conduction, convection and radiation (recapitulation only), thermal conductivity, qualitative ideas of Blackbody radiation, Wein’s displacement Law, Stefan’s law.
Unit-VIII: Thermodynamics
Chapter 12: Thermodynamics
Thermal equilibrium and definition of temperature (zeroth law of thermodynamics), heat, work and internal energy. First law of thermodynamics, Second law of thermodynamics: gaseous state of matter, change of condition of gaseous state -isothermal, adiabatic, reversible, irreversible, and cyclic processes.
Unit-IX: Behaviour of Perfect Gases and Kinetic Theory of Gases
Chapter 13: Kinetic Theory
Equation of state of a perfect gas, work done in compressing a gas.
Kinetic theory of gases – assumptions, concept of pressure. Kinetic interpretation of temperature; rms speed of gas molecules; degrees of freedom, law of equi-partition of energy (statement only) and application to specific heat capacities of gases; concept of mean free path, Avogadro’s number.
Unit-X: Oscillations and Waves
Chapter 14: Oscillations
Periodic motion – time period, frequency, displacement as a function of time, periodic functions and their application.
Simple harmonic motion (S.H.M) and its equations of motion; phase; oscillations of a loaded spring- restoring force and force constant; energy in S.H.M. Kinetic and potential energies; simple pendulum derivation of expression for its time period.
Chapter 15: Waves
Wave motion: Transverse and longitudinal waves, speed of travelling wave, displacement relation for a progressive wave, principle of superposition of waves, reflection of waves, standing waves in strings and organ pipes, fundamental mode and harmonics, Beats.
Students can also access the syllabus for other subjects by visiting Syllabus page of CBSE Class 11.
CBSE Syllabus for Class 11 Physics Practical
Below are the list of the experiments of Physics practicals.
Evaluation Scheme for Class 11 Physics Practical 2023-24
Topic
Marks
Two experiments, one from each section
7 + 7
Practical record (experiment and activities)
5
One activity from any section
3
Investigatory Project
3
Viva on experiments, activities and project
5
Total
30
CBSE Class 11 Physics Practical Syllabus
Section – A
CBSE 11 Physics Syllabus Experiments
1. To measure the diameter of a small spherical/cylindrical body and to measure internal diameter and depth of a given beaker/calorimeter using Vernier Callipers and hence find its volume. 2. To measure the diameter of a given wire and thickness of a given sheet using screw gauge. 3. To determine the volume of an irregular lamina using the screw gauge. 4. To determine the radius of curvature of a given spherical surface by a spherometer. 5. To determine the mass of two different objects using a beam balance. 6. To find the weight of a given body using parallelogram law of vectors. 7. Using a simple pendulum, plot its L-T2 graph and use it to find the effective length of second’s pendulum. 8. To study variation of time period of a simple pendulum of a given length by taking bobs of same size but different masses and interpret the result. 9. To study the relationship between force of limiting friction and normal reaction and to find the co- efficient of friction between a block and a horizontal surface. 10. To find the downward force, along an inclined plane, acting on a roller due to gravitational pull of the earth and study its relationship with the angle of inclination θ by plotting graph between force and sin θ.
CBSE 11 Physics Syllabus Activities
1. To make a paper scale of given least count, e.g., 0.2cm, 0.5 cm. 2. To determine mass of a given body using a metre scale by principle of moments. 3. To plot a graph for a given set of data, with proper choice of scales and error bars. 4. To measure the force of limiting friction for rolling of a roller on a horizontal plane. 5. To study the variation in range of a projectile with angle of projection. 6. To study the conservation of energy of a ball rolling down on an inclined plane (using a double inclined plane). 7. To study dissipation of energy of a simple pendulum by plotting a graph between square of amplitude and time.
Section – B
CBSE 11 Physics Syllabus Experiments
1. To determine Young’s modulus of elasticity of the material of a given wire. 2. To find the force constant of a helical spring by plotting a graph between load and extension. 3. To study the variation in volume with pressure for a sample of air at constant temperature by plotting graphs between P and V, and between P and 1/V. 4. To determine the surface tension of water by capillary rise method. 5. To determine the coefficient of viscosity of a given viscous liquid by measuring terminal velocity of a given spherical body. 6. To study the relationship between the temperature of a hot body and time by plotting a cooling curve. 7. To determine specific heat capacity of a given solid by method of mixtures. 8. To study the relation between frequency and length of a given wire under constant tension using sonometer. 9. To study the relation between the length of a given wire and tension for constant frequency using sonometer. 10. To find the speed of sound in air at room temperature using a resonance tube by two resonance positions.
CBSE 11 Physics Syllabus Activities
1. To observe change of state and plot a cooling curve for molten wax. 2. To observe and explain the effect of heating on a bi-metallic strip. 3. To note the change in level of liquid in a container on heating and interpret the observations. 4. To study the effect of detergent on surface tension of water by observing capillary rise. 5. To study the factors affecting the rate of loss of heat of a liquid. 6. To study the effect of load on depression of a suitably clamped metre scale loaded at (i) its end (ii) in the middle. 7. To observe the decrease in pressure with increase in velocity of a fluid.
Practical Examination for Visually Impaired Students of Class 11 Evaluation Scheme
Time: 2 Hours Max. Marks: 30
Topic
Marks
Identification/Familiarity with the apparatus
5
Written test (based on given/prescribed practicals)
10
Practical Record
5
Viva
10
Total
30
A. Items for Identification/Familiarity of the apparatus for assessment in practicals (All experiments).
Spherical ball, Cylindrical objects, vernier calipers, beaker, calorimeter, Screw gauge, wire, Beam balance, spring balance, weight box, gram and milligram weights, forcep, Parallelogram law of vectors apparatus, pulleys and pans used in the same ‘weights’ used, Bob and string used in a simple pendulum, meter scale, split cork, suspension arrangement, stop clock/stop watch, Helical spring, suspension arrangement used, weights, arrangement used for measuring extension, Sonometer, Wedges, pan and pulley used in it, ‘weights’ Tuning Fork, Meter scale, Beam balance, Weight box, gram and milligram weights, forceps, Resonance Tube, Tuning Fork, Meter scale, Flask/Beaker used for adding water.
B. List of Practicals
1. To measure diameter of a small spherical/cylindrical body using vernier calipers. 2. To measure the internal diameter and depth of a given beaker/calorimeter using vernier calipers and hence find its volume. 3. To measure diameter of given wire using screw gauge. 4. To measure thickness of a given sheet using screw gauge. 5. To determine the mass of a given object using a beam balance. 6. To find the weight of given body using the parallelogram law of vectors. 7. Using a simple pendulum plot L-T and L-T2 graphs. Hence find the effective length of second’s pendulum using appropriate length values. 8. To find the force constant of given helical spring by plotting a graph between load and extension. 9. (i) To study the relation between frequency and length of a given wire under constant tension using a sonometer. (ii) To study the relation between the length of a given wire and tension, for constant frequency, using a sonometer. 10. To find the speed of sound in air, at room temperature, using a resonance tube, by observing the two resonance positions.
Note: The above practicals of CBSE 11 Physics Syllabus may be carried out in an experiential manner rather than recording observations.
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Frequently Asked Questions on CBSE Class 11 Physics Syllabus
Q1
According to the CBSE Class 11 Physics Syllabus, which are the units of high marks weightage?
According to the CBSE Class 11 Physics Syllabus, physical world and measurement, kinematics and laws of motion are the units of high-mark weightage.
Q2
How is the practical syllabus of the CBSE Class 11 Physics divided into sections A and B?
The practical syllabus of the CBSE Class 11 Physics contains 10 experiments in section A and 10 experiments in section B with 7 physical activities mentioned for each.
Q3
Which are the basic concepts present in the CBSE Syllabus for Class 11 Physics?
The basic concepts present in the CBSE Syllabus for Class 11 Physics are Thermodynamics, Laws of Motion, Oscillations and Waves.
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