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Questions in physics

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

[Free] Decide whether each proposed addition or subtraction is possible. Every answer you enter has the correct unit symbol. | proposed addition or subtraction | Is this possible? | result | |---|---|---| | [tex]$52.000 m-17.000 mm=?$[/tex] | yes no | | | [tex]$71.0 m-36.0 s=?$[/tex] | yes no | | | [tex]$22.000 s+42.000 ms=?$[/tex] | yes no | | |---|---|---|

[Free] 8. Electrons with maximum kinetic energy of 3 eV are ejected from a metal surface by ultra-violet radiation of wavelength [tex]$1.5 \times 10^{-7} m$[/tex]. Determine the work function, threshold wavelength, and the stopping potential for the metal (Planck's constant, [tex]$h =6.62 \times 10^{-34} Js$[/tex]).

[Free] 1. Which of the following best describes density? A) How much space an object takes up, regardless of the amount of matter B) How tightly particles are packed in a given space C) How fast particles move when heated D) How far apart particles are in a vacuum 2. A balloon is left in the sun. What happens to the air inside the balloon? A) Particles move slower and get closer together → density increases B) Particles move faster and spread farther apart → density decreases C) Particles stop moving → density stays the same D) Particles move slower and spread farther apart → density decreases 3. Cooling a substance generally causes: A) Particles to move faster and spread farther apart → density decreases B) Particles to move slower and come closer together → density increases C) Particles to disappear density disappears D) Particles to move randomly → density stays the same 4. You place a cup of water outside on a hot day and another cup in the freezer. Describe what happens.

[Free] Blake is doing an experiment to find the relationship between string tension [tex]F _7[/tex], string linear density D, frequency of oscillation ([tex]f[/tex]) and wavelength ([tex]\lambda[/tex]) for a wave on a string. The student keeps the string tension and density constant. He sets the frequency of the string's oscillation and measures the wavelength. The known relationship is: [tex]\sqrt{\frac{F_T}{D}}=f \lambda[/tex] a. Rearrange the equation so the dependent variable is by itself on one side. [tex]\sqrt{\frac{F T}{P}}=f \lambda=\sqrt{\frac{F_T}{\sqrt{5}}} \times \frac{1}{\frac{1}{5}}[/tex] b. What variables could he graph to get a linear relationship? x : f y: c. Fill in the data table below with any additional data you need to linearize it. d. Plot your data, being sure to label your axes. \begin{tabular}{|c|c|c|} \hline \begin{tabular}{c} Frequency $(1 / s )$ \end{tabular} & \begin{tabular}{c} Wavelength $( m )$ \end{tabular} & $\frac{1}{f}$ \\\hline 200 & 1.22 & 0.005 \\\hline 400 & 0.61 & 0.0025 \\\hline 600 & 0.41 & 0.0017 \\\hline 800 & 0.31 & 0.0013 \\\hline \end{tabular}

[Free] Select the correct answer. Why does a solid change to liquid when heat is added? A. The spacing between particles decreases. B. Particles lose energy. C. The spacing between particles increases. D. The temperature decreases.

[Free] The sound level, \(\beta\), in decibels (dB), of a sound with an intensity of \(I\) is calculated in relation to the threshold of human hearing, \(I_0\), by this equation: \[\beta=10 \log \left(\frac{I}{I_0}\right)\] The threshold of human hearing is \(10^{-12}\) watts / meter\(^2\). The sound level of a jet plane is approximately 140 dB. The intensity of the sound of a jet plane is approximately _____ watts/meter\({}^2\)

[Free] 17. 2071 Set D Q.No. 10a Ultraviolet light of wavelength [tex]$3.6 \times 10^{-7} m$[/tex] is made to fall on a smooth surface of potassium. Determine maximum energy of emitted photo electrons and stopping potential. [4] Ans: [tex]$1.5 eV , 1.5 V$[/tex] 18. 2070 Supp. Set [tex]$B$[/tex] Q.No. 10a Electrons with maximum kinetic energy of 3 eV are ejected from a metal surface by ultra-violet radiation of wavelength [tex]$1.5 \times 10^{-7} m$[/tex]. Determine work function, threshold wavelength and the stopping potential for the metal (Planck's constant, [tex]$h =6.62 \times 10^{-34} Js$[/tex] ) [4] Ans: [tex]$5.275 eV ., 2.35 \times 10^{-7} m, 3 V$[/tex] 19. 2070 Set C Q.No. 10b The photoelectric threshold wavelength of a tungsten surface is 272 nm . Calculate the maximum velocity of the electrons ejected from this tungsten surface by ultraviolet radiation of frequency [tex]$1.45 \times 10^{15} Hz$[/tex]. ([tex]$h=6.62 \times 10^{-34} Js, c=3 \times 10^8 m / s, me=9.1 \times 10^{-31} kg$[/tex]) Ans: [tex]$7.1 \times 10^5 m / sec$[/tex]

[Free] A car drives 215 km West and then 85 km South. Find the distance and displacement of the car.

[Free] The speed of light is approximately 3.0 x 10^8 m/s. How would this be written in standard notation? A) 300,000 m/s B) 30,000,000 m/s C) 3,000,000 m/s D) 300,000,000 m/s