Concept explainers
(a)
The length of a pencil or a pen moving at a speed specified by the following situations:
(a) a bicycle at constant speed.
(b) a car travelling on a highway.
(c) a commercial jet liner at cruising altitude.
(a)
Answer to Problem 86Q
Solution:
In all the cases, there is a negligible change in the length of a pencil that is 15cms long.
Explanation of Solution
Given data:
A pencil or a pen travelling at a speed equal to that of a bicycle rider, a car travelling on a highway and a commercial jetliner at cruising altitude.
Formula used:
Write the expression for Lorentz transformation of length.
Here,
Explanation:
The speed of light is
Assume the length of pen to be
Assume the speed of a bicycle to be
Calculate the length of a pen, moving at a speed equal to the speed of a bicycle.
Refer to the expression for Lorentz transformation of length.
Substitute the known values:
Now, calculate the length of a pen, moving at a speed equal to the speed of a car travelling on the highway.
Refer to the expression for Lorentz transformation of length.
Substitute the known values:
Now, calculate the length of a pen moving at a speed equal to the speed of a commercial jet liner at cruising altitude.
Refer to the expression for Lorentz transformation of length.
Substitute the known values:
Conclusion:
Hence, the length of the pen is nearly same in all the three situations.
(b)
The length of a pencil or a pen travelling at a speed equal to the speed of the beam emitted by a spaceship at a speed of
(b)
Answer to Problem 86Q
Solution:
Explanation of Solution
Given data:
A pen travelling at a speed equal to the speed of a beam emitted by a spaceship towards the other at
Formula used:
Write the expression for Lorentz transformation of length.
Here,
Explanation:
The speed of light is
Assume the length of the pen to be
The speed of the pen is given to be
Calculate the length of the pen.
Refer to the expression for Lorentz transformation of length
Substitute
Conclusion:
Hence, the length of the pen or the pencil is
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Chapter 21 Solutions
Universe
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