Length contraction (25-14)

Question 1 of 4

Question

Speed of light in a vacuum

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Question

Speed of $S′$ relative to $S$

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Question

Length of the same object in a frame of reference $S$ in which the object is moving along its length.

{"title":"Length of an object in a frame of reference S in which it is at rest.","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"72,35,95,74\"}]"} {"title":"Speed of S′ relative to S","description":"Incorrect","type":"incorrect","color":"#ffff00","code":"[{\"shape\":\"rect\",\"coords\":\"249,15,282,51\"}]"} {"title":"Speed of light in a vacuum","description":"Wrong","type":"incorrect","color":"#00ff00","code":"[{\"shape\":\"rect\",\"coords\":\"254,73,278,99\"}]"} {"title":"Length of the same object in a frame of reference S in which the object is moving along its length.","description":"Correct!","type":"correct","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"1,38,25,74\"}]"}

Question

Length of an object in a frame of reference $S$ in which it is at rest.

{"title":"Length of an object in a frame of reference S in which it is at rest.","description":"Correct!","type":"correct","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"72,35,95,74\"}]"} {"title":"Speed of S′ relative to S","description":"Incorrect","type":"incorrect","color":"#ffff00","code":"[{\"shape\":\"rect\",\"coords\":\"249,15,282,51\"}]"} {"title":"Speed of light in a vacuum","description":"Incorrect","type":"incorrect","color":"#00ff00","code":"[{\"shape\":\"rect\",\"coords\":\"254,73,278,99\"}]"} {"title":"Length of the same object in a frame of reference S in which the object is moving along its length.","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"1,38,25,74\"}]"}

Review

If the rod is moving, $V$ is greater than zero and the factor $\sqrt{1-V^2/c^2}$ is less than 1. So the length $L$ of the moving rod is less than the length $L_{\mathrm{rest}}$ of the rod at rest. In other words, a moving object is shortened along the direction in which it is moving. This is called length contraction.