1. What is the SI unit of force?

It is named after Sir Isaac Newton, a physicist and mathematician who made significant contributions to our understanding of mechanics and the laws of motion. <p>One Newton is defined as the force required to accelerate a one-kilogram mass by one meter per second squared (1 N = 1 kg&middot;m/s&sup2;).</p> <p>This unit is fundamental in physics, particularly in mechanics, where it is used to quantify the effects of forces on objects.</p> <p>Forces can cause objects to accelerate, decelerate, change direction, or deform, depending on their magnitude and direction.</p> <p>Understanding the Newton allows scientists and engineers to calculate and predict the behavior of physical systems under the influence of various forces.</p>

2. What is Newton's second law of motion?

This law can be expressed mathematically as: 𝐹 = 𝑚a where:F is the net force acting on the object, 𝑚 is the mass of the object, a is the acceleration produced. <p><strong>Direct Proportionality to Force: </strong>This means that the acceleration ( 𝑎 a) of an object is directly proportional to the force ( 𝐹 F) applied to it.</p> <p>If you apply a greater force to an object, it will accelerate more. If you apply no force or a balanced force, the object will not accelerate (or will continue moving at a constant velocity if already in motion).</p> <p><strong>Inverse Proportionality to Mass:</strong> This part of the law states that the acceleration of an object is inversely proportional to its mass ( 𝑚 m).&nbsp;In simpler terms, a heavier object requires more force to achieve the same acceleration as a lighter object.</p> <p>Therefore, acceleration decreases as mass increases, assuming the force remains constant.</p> <p><strong>Units: </strong>In the International System of Units (SI), force is measured in newtons (N), mass in kilograms (kg), and acceleration in meters per second squared (m/s&sup2;).</p> <p>Newton's second law of motion is fundamental in understanding how objects respond to forces and how acceleration relates to force and mass.</p> <p>&nbsp;It forms the basis for calculating the dynamics of objects under the influence of external forces.</p>

3. What is the acceleration due to gravity on Earth?

<p>Acceleration due to gravity on Earth is approximately 9.8&thinsp;m/s2.</p> <p>This value represents the acceleration experienced by objects in free fall near the Earth's surface due to gravity.&nbsp;</p> <p><strong>Concept: 1. Definition: </strong>Acceleration due to gravity (g) is the acceleration that an object experiences when it falls freely under the influence of gravity.&nbsp;Near the surface of the Earth, this value is approximately constant and is denoted by g.</p> <p><strong>Concept: 2. Measurement:</strong> The standard value of g on Earth is commonly approximated as 9.8&thinsp;m/s2.</p> <p>This means that for every second an object falls, its velocity increases by 9.8&thinsp;m/s.</p> <p><strong>Concept: 3.</strong> <strong>Factors Influencing g: </strong>The actual value of g can vary slightly depending on factors such as altitude (height above sea level) and latitude (distance from the equator), but these variations are typically minor.</p> <p><strong>Concept: 4. Units:</strong> g is measured in meters per second squared (m/s&sup2;), which is the unit of acceleration in the International System of Units (SI).</p> <p>Understanding the value of g is crucial in various fields of physics, including mechanics, dynamics, and gravitational studies, as it governs the motion of objects falling under the influence of Earth's gravity.</p>

4. Who formulated the three laws of motion?

<p>Isaac Newton formulated the three laws of motion, which are fundamental principles in classical mechanics.&nbsp;</p> <p><strong>&nbsp;Newton's three laws of motion: </strong></p> <ol> <li><strong>First Law (Law of Inertia):</strong> An object at rest will remain at rest, and an object in motion will continue to move at a constant velocity (which could be zero if at rest) unless acted upon by an external force.</li> <li><strong>Second Law (Law of Acceleration):</strong> The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically, F=ma, where F is the force applied, m is the mass of the object, and a is the acceleration produced.</li> <li><strong>Third Law (Law of Action-Reaction): </strong>For every action, there is an equal and opposite reaction. This means that whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.</li> </ol> <p>Isaac Newton (1642&ndash;1727) developed these laws of motion in his work "Mathematical Principles of Natural Philosophy," published in 1687.</p> <p>These laws laid the foundation for understanding the motion of objects under the influence of forces, and they are still used today to describe the behavior of objects in everyday life, engineering, and astronomy</p>

5. What is the time taken by the earth to complete one rotation about its axis with regard to a fixed star?

<p class="MsoNormal">A sidereal day is the time Earth takes to rotate once relative to a fixed star. A solar day is the time Earth takes to rotate relative to the Sun.</p> <p class="MsoNormal">A shake, the smallest practical unit of time, equals 10⁻⁸ seconds. A tropical year, unrelated to solar eclipses, is the time for Earth to complete one orbit around the Sun, aligning with the equinoxes.</p>

6. Water does not fall out of a glass when it is inverted inside a satellite, which is orbiting very close to the earth’s surface. Which of the following is the best reason for this ?

When a glass of water is inverted inside a satellite orbiting close to Earth's surface, the water doesn't fall out because both the glass and the water experience the same gravitational acceleration (g) toward Earth's center. This lack of relative motion between them results in the water staying inside the glass.

7. Which of the following sounds is produced by earthquakes before the main shock waves?

Earthquakes emit low-frequency infrasound before the main shock waves, potentially alerting animals. Observations suggest that animals may sense these infrasounds, causing them to exhibit unusual behavior or become disturbed before an earthquake occurs, indicating their ability to detect seismic activity early.

8. The unit of Planck’s constant is

Planck's constant, representing physical action, shares dimensions with angular momentum, which is energy times time or momentum times distance. In the International System of Units (SI), Planck's constant is measured in joule-seconds (J·s) or equivalently in newton-meter-seconds (N·m·s), highlighting its fundamental role in quantum mechanics.

9. Farad is the unit of which of the following?

The Farad (F) is the SI derived unit of capacitance, measuring a capacitor's ability to store electric charge. Named after the English physicist Michael Faraday, it reflects his contributions to electromagnetism and electrochemistry. One farad equals one coulomb of charge per volt of potential difference.

10. Loudness of sound depends upon which of the following?

Sound has three key characteristics: pitch, loudness, and quality (or tone). Loudness is determined by the amplitude of the sound wave—the greater the amplitude, the louder the sound. Pitch depends on the frequency of the sound source, while quality (or tone) depends on the waveform shape.

11. During the free fall of the object, the decrease in potential energy, at any point in its path, appears as an equal amount of increase in ______.

The total mechanical energy of an object is the sum of its kinetic and potential energy. During free fall, the object's potential energy decreases while its kinetic energy increases by the same amount. This results in a continual transformation of gravitational potential energy into kinetic energy throughout its descent.

12. Which of the following has the similar properties to the Photons?

Photons, the fundamental particles of light, exhibit both particle and wave properties, enabling phenomena like refraction and diffusion. Unlike other elementary particles, photons are massless and always travel at the speed of light in a vacuum, making them unique in their behavior and interaction with matter.

13. For which of the following waves the Doppler effect holds true?

The Doppler effect, applicable to both sound and electromagnetic waves, describes the change in frequency due to motion. Approaching a stationary sound source at high speed raises the perceived pitch, while receding lowers it. This shift in observed frequency, caused by the relative motion between the source and the observer, is the Doppler effect.

14. Two plane mirrors are inclined at an angle of 90 degree to each other. The number of images formed for an object placed in between the two will be _?

The formula determines the number of images, and if the result isn't a whole number, it's rounded to the nearest integer. This approach ensures practical application, simplifying interpretation and usage where precise whole numbers are typically more relevant and useful.

15. What is the S.I unit of Pressure Energy?

Joule (J) is a unit of energy, not specifically pressure energy. Pressure energy, stored in a fluid due to force per unit area, is calculated as Pressure × volume. Its dimensional formula, M L² T⁻², signifies mass, length squared, and time squared, representing its units in the SI system.

16. What is the relation between the orbital velocity and the radius of the orbit for a given planet?

The orbital velocity of a satellite around a planet decreases with increasing radius of its orbit. This velocity is influenced by the mass of the central body (planet) and the distance from it (radius of orbit), adhering to the principles of gravitational attraction and centripetal force in orbital mechanics.

17. On which of these factors, the buoyancy depends?

Buoyancy is determined by two factors: 1. The volume of the object submerged in the fluid—more submerged volume increases buoyant force. 2. The density of the fluid—the denser the fluid, the greater the buoyant force exerted on the object, influencing its ability to float or sink.

18. The motion of an object under free fall is an example of which of the following?

Free fall of an object near Earth's surface is an example of uniform acceleration. Acceleration due to gravity causes the object to fall downward. This acceleration remains constant at approximately 9.8 m/s², causing the object's velocity to increase uniformly as it descends due to gravitational attraction.

19. Which of the following waves can be used to measure the speed of a approaching car?

Radio waves, part of the electromagnetic spectrum with wavelengths longer than infrared light, operate at frequencies from 30 Hz to 300 GHz. They're used in radar systems to measure the speed of approaching cars by analyzing the Doppler shift in the radio waves reflected off the moving vehicle.

20. What is the angular acceleration of a body moving with constant angular velocity?

When a body moves with a constant angular velocity, its angular acceleration is zero because there is no change in its angular velocity over time. In circular motion, angular acceleration represents how quickly the angular velocity changes, indicating the rate of change in the rotational speed or direction of the object.

21. The pointer or arrow of the magnetized needle of a compass indicates which among the following?

The north pole of a compass needle points towards magnetic north, which is not precisely aligned with the Earth's geographic North Pole. Instead, it corresponds to Earth's magnetic South Pole near the geographic North Pole. The angular difference between magnetic north and true north, known as magnetic declination, varies by location due to Earth's complex geomagnetic field. Maps typically use true north as a reference, and magnetic declination is indicated on map legends to help correct compass readings for accurate navigation and orientation relative to geographic landmarks.

22. Which among the following correctly represents a Parsec?

An astronomical unit (AU) is a unit of measurement used in astronomy, representing the average distance from Earth to the Sun, approximately 149.6 million kilometers or 92.96 million miles. It's fundamental for measuring distances within our solar system. In contrast, a light-year is the distance light travels in one year, about 9.46 trillion kilometers or 5.88 trillion miles. Therefore, 3.3 light-years is roughly 31.15 trillion kilometers or 19.38 trillion miles. This distance scale helps astronomers comprehend vast cosmic distances beyond our solar system, essential for studying stars, galaxies, and the expansive universe.

23. Speed of light will be maximum in which of the following mediums?

24. Large Underground Xenon experiment (LUX) is being carried out in which country?

The Large Underground Xenon experiment (LUX) is situated 1,510 meters underground at the Sanford Underground Laboratory in Lead, South Dakota. LUX aims to detect dark matter particles using a tank filled with liquid xenon, shielded from cosmic rays, to observe rare interactions that could reveal the nature of dark matter in the universe.

25. Who was the first to state the principle of floatation?

Archimedes, the Ancient Greek scientist, formulated the principle of flotation, stating that when a body is partially or fully immersed in a fluid, it experiences an apparent loss in weight equal to the weight of the fluid displaced. This principle explains buoyancy and is fundamental in understanding objects' behavior in liquids.

26. Which of the following is true about a concave lens?

The power of a convex lens is positive because it converges light rays to a focal point, aiding in focusing. In contrast, a concave lens diverges light rays, causing them to spread out. Its power is negative, indicating its ability to diverge light rather than converge it.

27. Which one of the following layers of the atmosphere is responsible for the deflection of radio waves?

The ionosphere, a region of the Earth's atmosphere, reflects radio waves due to its ionized gas particles. These ions enable radio waves to bounce off them, facilitating long-distance communication through radio propagation. This phenomenon is crucial for various applications, including radio broadcasting, long-distance communication, and radio astronomy.

28. Decibel is the unit used for__:

The decibel (dB) measures sound intensity logarithmically relative to a reference level, commonly used in acoustics, electronics, and engineering. It quantifies power or intensity ratios, providing a compact scale to describe large variations in sound levels, from whispers to jet engines. It's essential for precise measurement and control in diverse scientific and engineering fields.

29. The joint process of vapourisation and condensation is called :

Condensation is the process where a vapor turns into a liquid or solid state. Vaporization is the transformation from liquid or solid to gas. Distillation involves heating a liquid to produce vapor, which is then cooled and collected, separating it from the original liquid through both vaporization and condensation processes.

30. Time period of a pendulum will ______ at the Moon to that of on the Earth

On the Moon, gravity ('g') is weaker than on Earth, so the acceleration due to gravity is lower. A pendulum's time period, which depends on 'g', increases with a decrease in gravity. Thus, a pendulum would take longer to complete each swing on the Moon compared to Earth.

31. Which one of the following processes is responsible for the glittering of air bubble rising through water?

Total internal reflection causes glittering when light from a denser medium, like water, meets a less dense medium, such as air in a bubble. The light reflects back into the water instead of refracting out, creating a sparkling effect visible to our eyes, known as glittering.

32. Intensity of any wave is proportional to which of the following?

The energy and intensity of a wave are indeed proportional to the square of its amplitude. When intensity decreases with distance (r) from the source at a rate of 1/r², the amplitude decreases at a slower rate of 1/r. This relationship highlights how wave characteristics change with distance from the source.

33. The time period of a sound wave is 0.01 seconds. What will be its frequency in Hz?

Frequency (f) is the rate at which wave cycles occur per second. If the period (T) of a wave is 0.01 seconds, the frequency is calculated using the formula f = 1/T. Substituting T = 0.01 seconds gives f = 1/0.01 = 100 Hz, indicating the wave completes 100 cycles per second.

34. What is the S.I. unit of electric charge?

The coulomb (C) is the SI unit of electric charge, defined as the charge carried by nearly 6 × 10^18 electrons. It quantifies the amount of electric charge transferred through a conductor in an electric current. This standardization allows for precise measurement and calculation in electrical systems and phenomena.

35. At which of the following speeds radio waves travel?

Radio waves, a type of electromagnetic radiation, travel at the speed of light, which is nearly 300,000 kilometers per second. This rapid speed allows a beam of light to circumnavigate the Earth's equator over 7 times in just one second, highlighting the immense velocity of electromagnetic waves through space.

36. What is Reynolds number?

The Reynolds number (Re) is a dimensionless parameter used to predict whether fluid flow will be turbulent or laminar. It quantifies the ratio of inertial forces (resulting from fluid motion or obstacles) to viscous forces. Higher Reynolds numbers indicate turbulent flow, while lower numbers suggest laminar flow, aiding in fluid dynamics analysis.

37. Which of the following is true about metals?

Metals and alloys exhibit low resistivity, typically ranging from 10^-8 ohm meters to 10^-6 ohm meters. This low resistivity signifies their ability to conduct electricity efficiently. It stems from their atomic structure, where free electrons can move easily through the material, facilitating the flow of electric current with minimal resistance.

38. Which of the following represents the speed of a sound wave?

The speed of sound (s) in a medium is determined by the product of its wavelength and frequency, represented as s = wavelength × frequency. This formula relates how quickly disturbances in pressure and density propagate through the medium, influenced by factors like temperature and medium composition.

39. What is the cumulative electric charge of an electric dipole?

An electric dipole consists of two point charges of equal magnitude but opposite polarity. Despite their individual charges, the dipole as a whole exhibits no net charge due to their cancellation. In nature, dipoles tend to align with the Earth's magnetic field, influenced by magnetic forces rather than electrostatic charges.

40. Which of the following properties of a material make it suitable to become a permanent magnet?

In selecting magnetic materials, high retentivity ensures strong magnetism, retaining magnetization effectively. High coercivity prevents magnetization loss from external influences like stray fields or temperature changes. High permeability facilitates efficient magnetic field conduction. These properties are crucial for applications requiring stable and reliable magnetic behavior, such as in permanent magnets and magnetic storage devices.

41. What is Mass defect of a nucleus?

The mass defect refers to the difference in mass between a nucleus and the sum of its constituent particles (protons and neutrons). This difference arises because some mass is converted into binding energy during nuclear formation, as per Einstein's equation E=mc2, where E is energy, mmm is mass, and c is the speed of light.

42. What is the effect of increase in radius of orbit on the binding energy of a satellite?

<p>As the radius of orbit of a satellite increases, the binding energy decreases. This is because the gravitational force between the satellite and the celestial body weakens with distance. Therefore, the satellite requires less energy to maintain its orbit as it moves farther away from the central body.</p>

43. What is the equilibrium distance for Hydrogen atoms?

<p>The equilibrium distance between atoms, such as hydrogen atoms, refers to the stable separation where the attractive and repulsive forces between them balance out, resulting in minimal potential energy.</p> <p>At this point, the interatomic force is zero, ensuring the atoms maintain a stable configuration unless acted upon by external forces or changes in conditions.</p>

44. What is the Gaussian unit of kinematic viscosity?

The stokes (symbol: St) is a unit of kinematic viscosity, measuring the resistance of a fluid to flow under gravity. One stoke equals 10,000 square meters per second. It's commonly used in fluid dynamics and engineering to characterize how easily fluids move through a medium, important in various scientific and industrial applications.

45. What do we call the temperature at which the liquid and the vapour states of the substance coexist?

The boiling point of a substance is the temperature at which its liquid and vapor phases coexist in equilibrium. At this temperature, the vapor pressure of the liquid equals the external pressure, causing bubbles of vapor to form throughout the liquid, leading to its conversion into vapor.

46. Which of the following represents the condition for floatation?

According to Archimedes' principle, an object submerged or floating in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces. If this buoyant force (Fb) equals the object's weight (mg), the object will float. If Fb is less than mg, the object sinks; if greater, it rises.

47. A light year is a measure of__?

A light-year represents the distance that light travels in a vacuum over the course of one year, as defined by the International Astronomical Union (IAU). It spans nearly 10 trillion kilometers (or about 6 trillion miles), serving as a fundamental unit for measuring vast distances in astronomy and cosmology.

48. Which term is not associated with sound wave?

The candela (cd) is the SI unit measuring luminous intensity, which quantifies the brightness of light emitted from a point source in a specific direction. Originally based on the light emitted by a candle, it now defines intensity in terms of power per solid angle and is crucial in lighting and optics standards.

49. Which among the following determines the pitch of a sound?

The pitch of a sound corresponds directly to the frequency of its vibrations. Higher frequencies result in higher pitches. Frequency, measured in Hertz (Hz), quantifies how often a sound wave oscillates per second. For instance, a sound vibrating at 100 Hz produces a pitch perceived as lower compared to higher frequencies.

50. Lamberts law is related to which of the following?

Lambert's Law describes how the intensity of light emitted or reflected from a surface depends on the angle of observation. A Lambertian surface reflects light equally in all directions, maintaining constant radiance from any viewing angle. This property is idealized in optics and used to model diffuse reflection in various applications.

51. A radioactive substance does not undergo any change (in mass or charge) during__:

Gamma-rays are a form of electromagnetic radiation with no rest mass or charge, unlike particles such as electrons or protons. They are high-energy photons emitted during nuclear reactions or radioactive decay. Despite their wave-like nature, they interact with matter through processes like Compton scattering and photoelectric effect, behaving both as waves and particles.

52. In the remote control of television, electromagnetic waves used are__:

In home television remote controls, infrared (IR) rays are used to transmit signals to the television set. These signals are received by IR sensors, not thermionic valves (which are vacuum tubes). The sensors interpret the IR signals to control various functions of the television, such as changing channels, adjusting volume, or accessing menus.