11th Class Physics Laws Of Motion / गति के नियम Question Bank 11th CBSE Physics NLM, Friction, Circular Motion

  • question_answer
    Earth is a rotating frame of reference, even then it is considered as inertial frame of reference for all practical purposes. Why?

    Answer:

                    Earth is revolving around the sun. Therefore, it possesses centripetal acceleration. Therefore, it should be treated as non inertial frame of reference. However, value of centripetal acceleration of earth, \[a=\frac{{{\upsilon }^{2}}}{R}={{\omega }^{2}}R={{\left( \frac{2\pi }{T} \right)}^{2}}R=\frac{4{{\pi }^{2}}R}{{{T}^{2}}}\] Putting  R = 1\[A.U.\,=1.496\,\times {{10}^{11}}m\], and \[T=365\frac{1}{4}days=\frac{1461}{4}\times 24\times 60\times 60\sec =3.16\times {{10}^{7}}\sec .\], we get \[a=4\times \frac{22}{7}\times \frac{22}{7}\times \frac{1.496\times {{10}^{11}}}{{{\left( 3.16\times {{10}^{7}} \right)}^{2}}}=0.006m/{{s}^{2}}\], which is negligibly small compared to acceleration due to gravity (\[\text{g}=\text{9}\text{.8 m}/{{\text{s}}^{\text{2}}}\]). Hence for terrestrial experiments, earth can be considered as an inertial frame.


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