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Questions in physics

[Answered] A hoop of radius R rests on a smooth horizontal surface. A similar hoop moves past it at a constant velocity v. The velocity v_A of the upper point of intersection of the hoops as a function of the distance d between their centres is \(\frac{v}{k\sqrt{1-\left(\frac{d}{2R}\right)^2}}\), assuming that the hoops are thin and the second hoop is in contact with the first hoop as it moves past the latter. Find the value of k.

[Answered] Electric shock severity depends on: A. Voltage B. Area and pressure of contact. C. Amount of moisture on contact surfaces. D. All of the above

[Answered] 10. An object accelerates 16.3 m/s² when a force of 4.6 newtons is applied to it. What is the mass of the object? 11. An object with a mass of 2.0 kg has a force of 9.0 newtons applied to it. What is the resulting acceleration of the object? 12. An object with a mass of 2000 kg has a force of 6.2 newtons applied to it. What is the resulting acceleration of the object? 13. An object with a mass of 3.2 kg has a force of 7.3 newtons applied to it. What is the resulting acceleration of the object? 15. An object accelerates 8.2 m/s² when a force of 20.1 newtons is applied to it. What is the mass of the object?

[Answered] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Answered] A gas has experienced a small increase in volume but has maintained the same pressure and number of moles. According to the ideal gas law, how has the temperature of the gas changed? A. It has increased two times. B. It has increased slightly. C. It has decreased slightly. D. It has stayed the same.

[Answered] Which of the following statements describes something that needs to be corrected in Lily's report? A. She needs to change the exclamation points to periods. B. The first sentence is incomplete. C. There should be no comma in the third sentence. D. She needs to add a comma in the third sentence.

[Answered] 1. The speed of a sound wave is 340 m/s and its wavelength is 34 m. Is it audible to human beings? Justify your answer. 2. Wavelength of a sound having a frequency 2 kHz is 35 cm. How much time will it take to travel 100 m? 3. Limit of audibility to human beings is 20 Hz to 20000 Hz. If so, what will be the limit of a wavelength of sound waves that are audible to human beings? (Speed of sound in air = 340 m/s)

[Answered] I. Say "True" if the statement is correct and "False" if wrong. 1. Magnetic field lines always flow from the North Pole to the South Pole outside the magnet. 2. Iron, cobalt and nickel are examples of magnetic materials. 3. The strength of magnetic field increases with distance from the magnet. 4. When connecting lamps in series, they will generally be brighter than if the same lamps were connected in parallel to the same voltage source. 5. Two parallel wires carrying currents in the same directions will attract each other. II. Match the following from column B to A 6. Radio waves 7. Micro waves 8. Infrared 9. Visible light 10. Ultraviolet 11. X-rays 12. Gamma rays A. Used in remote control & night vision cameras B. Have the shortest wave length & highest energy. C. Can cause sun burn, used in sterilization. D. Emitted by stars, visible to the human eye. E. Used in medical imaging to view inside the body. F. Used to cook food & in radar system. G. Longest wave length; used for communication III. Choose the best answer from the given alternatives. 13. The image formed on the retina of a human eye is A. Virtual & erect B. Real & inverted C. Real & erect D. Virtual & inverted 14. Which of the following defects of vision is corrected using a concave lens? A. Hypermetropia B. Presbyopia C. Myopia D. Astigmatism 15. The least distance of distinct vision for a normal human eye is A. 10cm B. 25cm C. 50cm D. 100cm 16. Which optical instrument uses total internal reflection? A. Periscope B. Microscope C. Telescope D. Binoculars 17. Which of the following are the primary colors of light? A. Red, yellow, blue B. Red, green, blue C. Cyan, magenta, yellow D. Red, blue, black 18. Which color is subtracted when white light passes through a yellow pigment? A. Red B. Green C. Blue D. Magenta

[Answered] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Answered] The mass of a cubical object is (235.1 ± 0.1) g. If the volume of the object measures (5.25 ± 0.05) cm³, what is its density?