Explanation: Dispersion Forces. London forces (dispersion forces, weakest intermolecular force) are the temporary attractive force due to the formation of temporary dipoles in a nonpolar molecule. Dipole-Induced Dipole Forces – a weak attraction that results when a polar molecule induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species. Dipole-Dipole Forces – Appealing force among the polar molecules. Hydrogen bond forces – An interaction that involves a hydrogen atom

Explanation: Sliding friction is greater than rolling friction. Rolling friction (rolling drag), is the force resisting the motion when a body rolls on a surface.

Explanation: Newton’s second law, which states that the force (F) acting on a body is equal to the mass (m) of the body multiplied by the acceleration (a) of its center of mass, F = ma.

Explanation: Weak Nuclear Force – Very Short 10-16 m, (Range), 10-13(Relative Strength). Gravitational Force – Infinite (Range), 10-39 (Relative Strength), Electromagnetic Force – Infinite (Range), 10-2 (Relative strength), Strong Nuclear Force – Short Nuclear size 10-15m (Range), 1(Relative Strength).

Explanation: Velocity. Acceleration is defined as the rate at which an object changes its velocity. It is a vector quantity. Unit of acceleration is the metre per square second (𝑚/𝑠 ).

Explanation: Difference. Net force is the sum total of all the forces which are acting on the body. Forces applied on an object in the same direction add to one another.

Explanation: Area. Thrust acting per unit area is known as pressure i.e. Pressure = Thrust/Area.

Explanation: A conservative force is one in which work done by or against it depends only on the starting and ending points of a motion. It does not depend upon the path taken during the work. The stored energy is recoverable as work.

Explanation: Torque. Scalar quantities have only magnitude (Examples – Energy, Mass, volume) while vector quantities have both magnitude and direction (Examples – Acceleration, Force, Momentum).

Explanation: When sound is reflected. Echo : The sound is heard more than once because of the time difference between the initial production of the sound waves and their return from the reflecting surface. Applications of echo – Measuring Depth and Height, Measuring Distance, Medical Diagnosis.

Explanation: Aluminium. The speed of sound is highest at 25°C and it is 6420m/s. Solids have molecules compact together. So usually, speed of sound is more in Solids compared to liquids and more in liquid than gases. Nickel – Good conductor of heat and electricity. Steel – Alloy of iron and carbon.

Explanation: Sound is a mechanical wave and needs a material medium like air, water, steel etc. for its propagation. It cannot travel through vacuum. Audio Frequency spectrum of the human ear is to be between 20 Hertz and 20,000 Hertz. Speed of sound in different mediums: Water (Sea) – 1531 m/s, Water (distilled) – 1498 m/s, Air – 346 m/s.

Explanation: Square. The loudness of sound is expressed in the units called the Decibel. The symbol of the decibel is dB. The sound pressure level of audible sound ranges from 0 dB through 120 dB.

Explanation: Acoustics. Optics is the branch of physical science that deals with the properties and phenomena of both visible and invisible light. Photonics is the study of light and other types of radiant energy whose quantum unit is the photon. Astrophysics is a branch of space science that applies the laws of physics and chemistry to seek to understand the universe.

Explanation: 1 kilohertz = 1000 oscillation per second. 10 oscillation per second = = 0.01 kilohertz. 10/ 1000

Explanation: In the first mode of vibration of the air column, there is one node and one antinode. In the second mode of vibration of the air column, two nodes and two antinodes are formed. This shows that only odd harmonics are present in the modes of vibrations of the air column closed at one end.

Explanation: 1498 m/s. The speed of sound in a medium can be determined by the equation: v =(Kp)-1/2 Where , v = speed of sound, K = compressibility and p = density. Speed of sound in air = 343 m/s, Speed of sound in water (at normal temperature and pressure) = 1498 m/s।

Explanation: Ultrasonic waves. They emit and collect the rays emitted by them. If the complete rays are collected then there is prey in the path of the bat. Otherwise there is no prey in its path.

Explanation: 343 m/sec. The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium. At 20°C, the speed of sound in air is about 343 meters per second, or a kilometer in 2.9 s or a mile in 4.7 s.

Explanation: The speed of sound in air is about 343 meters per second. Light travels at a speed of 300,000 km/s (186,000 mi/s) from a stationary source. Time taken by Light – Moon to Earth: 1.3 seconds and Sun to Earth (1 AU) : 8.3 minutes.

Explanation: Newton’s law of universal gravitation – Any particle of matter in the universe attracts another one with a force varying directly as the product of the masses and inversely as the square of the distance between them. G’ is denoted as the gravitational constant. Value of G = 6.67×10-11 Nm2/kg2 . Tides are caused by the combined gravitation attraction of the Sun and Moon on the Earth.

Explanation: Gravity : The universal force of attraction acting between all matter in the Universe. Anything that has mass, also has gravity. Isaac Newton discovered the laws of gravity and motion. The value of the acceleration due to the gravity on earth is 9.8 m/s2 . The SI unit of gravity is the newton (N).

Explanation: Kepler’s Third Law : The square of the period of revolution of any planet is directly proportional to the third power of the semi-major axis of the elliptical orbit of that planet. Hubble’s Law : The velocity of the galaxy, which is also known as the redshift, is directly proportional to its distance. Hubble’s law formula = v = H0d. Bragg’s Law : 2dsin(θ)=nλ, where, d (distance between crystal lattice planes), θ (Angle of incidence), n (Integer), λ is the wavelength of the X-rays. Copernicus’s Law : Proposed a heliocentric system, that the planets orbit around the Sun.

Explanation: Johannes Kepler. Three laws of planetary motion : First law – The orbit of a planet is an ellipse with the Sun at one of the two foci. Second law – A line segment joining a planet and the Sun sweeps out equal areas in equal intervals of time. Third law – The square of a planet’s orbital period is proportional to the cube of the Length of the semi-major axis of its Orbit

Explanation: Galileo Galilei (father of observational astronomy, modern physics and the scientific method). He is known for observations of the Moon, phases of Venus, moons around Jupiter, sunspots.

Explanation: LIGO (Laser Interferometer Gravitational-Wave Observatory) is a large-scale physics experiment and observatory to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool.

Explanation: (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i). Potential energy – The stored energy in any object or system by virtue of its position or arrangement of parts. Potential energy changes into Kinetic Energy when an object moves. Chemical energy – energy stored in the bonds of atoms and molecules. Examples of chemical energy – Batteries, biomass, petroleum, natural gas, and coal.

Explanation: Kinetic Energy – The energy an object has because of its motion. Potential Energy : Energy that is stored in an object due to its position or condition. Examples – Arrow and the stretched string on the bow, water at the top of the waterfall. Radiant Energy : Energy of electromagnetic and gravitational radiation. Examples – Produce heat, light, rays. Elastic Energy : Energy stored in an object due to a force that temporarily changes its shape. Example – Compressed spring, archer’s stretched bow.

Explanation: Average kinetic energy (KE) = 3 2 𝐾𝑇 Boltzmann constant is = K Temperature (T) = 25 0C Value of degree Celsius to Kelvin = T = 0C + 273 T = 25 + 273 ⇒ T = 298 K The value of Boltzmann constant (K) is 1.38 x 10-23 J/K Average KE = 3 2 𝐾𝑇 Average KE = (1.38 x 10-23 J/K) (298K) 3 2 Average KE = 6.17 x 10-21 J.

Explanation: 35 J. Given, Force applied on a brick (F) = 7 N, Displacement (s) = 5 m. Angle (θ) = 0°. Since, Work done = Force × displacement × cos θ, ⇒ Work done = 7 × 5 × cos 0°, (cos 0° = 1) ⇒ Work done = 35 joules.

Explanation: Kinetic energy (K.E.) is directly proportional to the mass of the object and to the square of its velocity: K.E. = 1/2 m v 2 ( “m” – mass of the object, “v” – velocity), Unit is joule (J). Examples: walking, falling, Flying airplane. Gravitational potential energy (GPE) = m⋅g⋅h (here, m is mass in kilograms, g is the acceleration due to gravity (9.8 m/s2 on earth), h is the height above the ground in meters).

Explanation: Chemical energy into electrical energy. Energy conversion devices : Electric Generator – Mechanical energy into electrical energy. Electric motor – Electrical energy into mechanical energy. Microphone – Sound energy into electrical energy. Loudspeaker – Electrical energy into Sound energy. Sitar – Mechanical energy into sound energy.

Explanation: Kinetic Energy = mv2 . m = 1 2 mass, v = velocity. Law of conservation of energy: energy can neither be created nor be destroyed; rather, it can only be transformed or transferred from one form to another. Conservative force – doesn’t depend on path, Examples – Gravitational Force, Spring Force, and Electrostatic force between two electric charges. Total mechanical energy = Potential energy + Kinetic energy.

Explanation: Rectilinear Motion is a linear motion in which the direction of the velocity remains constant and the path is a straight line like a parade of soldiers. Periodic motion is a motion repeated in equal intervals of time like a bouncing ball. Rotational motion is the motion of an object around a circular path, in a fixed orbit like a spinning wheel. Oscillatory motion is defined as the to and fro motion of the body about its fixed position like a simple pendulum.

Explanation: Position-time. There are three equations of motion (given by Issac Newton) that can be used to derive components such as displacement(s), velocity (initial and final), time(t), and acceleration(a). They are First: v = u + at (velocity-time), Second: s = ut + ½ at² (position-time), Third: v2 = u2 + 2as (position-velocity).

Explanation: V = W/Q . In an electrical circuit, the potential between two points (V) is defined as the amount of work done (W) by an external agent in moving a unit charge (Q) from one point to another.

Explanation: Kinetic. In Hydropower plants, A turbine converts the potential energy of water into kinetic energy, the kinetic energy of falling water into mechanical energy and then a generator converts the mechanical energy into electrical energy. Largest Hydroelectric power station in India: Koyna Hydroelectric Project (Maharashtra); First: Sidrapong Hydroelectric Power Station (West Bengal).

Explanation: Principle of conservation. It led to the development of the first law of thermodynamics – Energy can neither be created nor be destroyed ,Although, it may be transformed from one form to another.

Explanation: Mechanical (KE + PE). Kinetic energy (KE) is energy possessed by an object in motion (KE = 1/2 mv2 ). Potential energy (PE) is the stored energy that depends upon the relative position of various parts of a system (PE = mgh where m is the mass, g is the acceleration and h is the height).

Explanation: Gravitational potential energy is the energy stored in an object as the result of its vertical position or height. Examples – River water at the top of a waterfall, Ripe fruit before it falls.

Explanation: Particle nature. Photoelectric effect is the phenomenon of emission of electrons from the surface of the metal when the light of suitable frequency falls on it. Concerned Nobel Prize – Albert Einstein (1921) and Robert Andrews Millikan won Nobel (1923). Dual nature – Light behaves like a particle (known as photon), which explains how the light travels in straight lines and also behaves as the wave, which explains how light bends (or diffract) around an object.

Explanation: Guglielmo Marconi. He transmitted radio waves across the English Channel. Award – The Nobel Prize in Physics (1909). Scientists and Their Inventions : Michael Faraday – Electromagnetic induction. Telephone – Alexander Graham Bell. Printing Machine – Johannes Gutenberg. Marie Curie and Pierre Curie are remembered for her discovery of radium and polonium.

Explanation: Periodic motion : Examples – A rocking chair, a bouncing ball, a vibrating tuning fork.

Explanation: L waves. The S wave is about 1.7 times slower than the P wave. L waves have long wavelengths, and lead most of the earthquake’s structural damage.

Explanation: 1842. Applications of the doppler effect : Sirens, Radar, Astronomy, Medical Imaging, Blood Flow Measurement, Satellite Communication, Vibration Measurement, Developmental Biology, Audio, Velocity Profile Measurement etc.

Explanation: X-rays > Infrared > Microwaves > Radio waves. Gamma rays (smallest wavelength and highest frequency). Radio Waves (longest wavelength and lowest frequency). Wavelength is inversely proportional to frequency. Frequency (f) : The number of waves passing a point in a second. The unit of frequency is measured in hertz (Hz). Wavelength (λ) : The distance traveled by the wave in one time period of vibration of the particle of medium. Its SI unit is a meter (m).

Explanation: Radio waves. Examples – Cellular Networks, RADAR, Radio Astronomy, Satellite Communication etc. Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Ultraviolet rays is a form of electromagnetic radiation with wavelengths from 10 nm to 400 nm, shorter than that of visible light, but longer than X-rays. Infrared waves are electromagnetic radiation with wavelengths longer than those of visible light.

Explanation: Seven. The common designations are – Radio waves, Microwaves, Infrared (IR), Visible light, Ultraviolet (UV) light, X-rays, and Gamma-rays.

Explanation: Magnetic resonance imaging is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. Computed tomography (CT) is an imaging procedure that uses special x-ray equipment to create detailed pictures, or scans, of areas inside the body. Fluoroscopy is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. A positron emission tomography (PET) scan is an imaging test that can help reveal the metabolic or biochemical function of your tissues and organs.

Explanation: bob. Other Terminology of Pendulum : Pivot – The point of attachment from which a pendulum swings, Amplitude – The distance from which the pendulum is released from the vertical. A Pendulum is a mechanical system, its motion is oscillatory motion.