Physics MCQs

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Friction is the main reason for any object to come to rest. It is the main reason for the stability of the objects on earth.

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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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The normal temperature for a human body is 310 kelvins is 36.85 degrees Celsius. The average normal body temperature is generally accepted as 98.6°F.

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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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X-ray crystallography helps to determine the atomic and molecular structure of a crystal. The crystalline structure performs the diffraction and it causes a beam of incident X-rays to diffract into many specific directions.

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The reason is the anomalous expansion of water. The maximum density of water occurs at 4°C. So the water expands whether it is heated above 4°C or cooled below 4°C.

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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.

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Thermodynamics is that branch of physics which deals with heat and temperature and their relation to energy (such as mechanical, electrical, or chemical energy) and work. The behaviour of these quantities is governed by the four laws of thermodynamics

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bar, torr and Pascal are the units used for measuring pressure whereas shake is a unit of time. 1 bar = 10⁵ Pa 1 bar = 760 torr 1 bar = 1 atmospheric pressure Shake is the smallest practical unit of time. 1 shake = 10^-8s

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The unit of Velocity Gradient is s^-1(per second) Velocity Gradient = Velocity/time Velocity gradient shows that how the velocity of a fluid changes between different points within the fluid.