Physics MCQs

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Bats use SONAR (Sound Navigation & Ranging).Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

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Kelvin is the base unit of temperature (SI unit), having the unit symbol K. The Kelvin temperature scale has an absolute zero (0°K) below which temperatures do not exist. It is the lowest possible temperature. At this temperature there is no motion and no heat. It is equivalent to 0°K, or -273.15° C, or at -460° F.

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Ability of a material to support the formation of a magnetic field within itself is Permeability. It is the measure of the resistance of a material against the formation of a magnetic field.

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Infrared waves are used in the night vision apparatus such as night vision goggles. Active infrared night-vision combines infrared illumination of spectral range 700–1,000 nm (just below the visible spectrum of the human eye) with CCD cameras sensitive to this light.

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The term “Isopycnic” refers to two substances having the same density. It is derived from the Greek words “iso,” meaning equal, and “pycnos,” meaning dense. In scientific contexts, isopycnic conditions are often used in centrifugation techniques to separate particles based on their density, such as in the purification of DNA or proteins.

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Kinetic Energy is a product of half the Mass times Velocity Squared. When the velocity is doubled, the Kinetic energy would go up four times. If velocity is tripled, kinetic energy would go up nine times. If velocity is increased by 1.5 times the Kinetic energy would go up by 1.5×1.5=2.25 times.

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The velocity of an object undergoing uniform circular motion is always changing (because the direction is always changing). Further, since the acceleration is centripetal, it must always point toward the center of the circle; so, as the object moves around the circle, the acceleration vector is also constantly changing direction. Notice that for an object in uniform circular motion, both the velocity and the acceleration are changing because the directions of these vectors are always changing, even though their magnitudes stay the same. In this question, only speed remains unchanged.

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Low Earth Orbit (LEO) is more prone to space debris or space junk. This is because space debris is more concentrated in orbits closer to Earth. Most debris is within 2,000 km (1,200 miles) of Earth’s surface.
Space debris orbits the Earth at tremendous speeds, about 15,700 miles per hour (25,265 kph) in low Earth orbit. In the event of a collision, it could cause significant damage to a satellite or spacecraft.
Experts are concerned about the amount of space debris in regions that are too high to benefit from the cleansing effects of Earth’s atmosphere. They believe that if there is too much space junk in orbit, it could result in a chain reaction where more and more objects collide and create new space junk.

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The motion of a projectile is two dimensional motion consisting of (i) horizontal motion and (ii) vertical motion. Hence, at any instant, the velocity of a projectile has two components (i) horizontal component and (ii) vertical component. The horizontal component remains unchanged throughout the flight as there is no acceleration in horizontal direction. The vertical component is continuously affected by the force of gravity. Thus, the horizontal motion is uniform motion but the vertical motion is uniformly accelerated motion.)

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X-rays were discovered by Wilhelm Conrad Roentgen. W.C Roengten discovered X-Rays while actually working on Cathode rays. X-rays is a form of electromagnetic radiation having a wavelength ranging from 0.01 to 10 nanometers and frequencies in the range 30 petahertz to 30 exahertz. Some Uses of X-Rays: The main use of X-rays is in medicine to check for a broken bone inside body. X-rays can also be used to kill cancer cells. X-rays are used at security checks at airports, railway stations etc. to check customers and baggage. X-rays are also used art historians to see if a picture has been painted on top of an older one. X-ray diffraction is also very important in spectroscopy and as a basis for X-ray crystallography.