Checking the Lorentz transformation

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The discussion revolves around the confusion in applying the Lorentz transformation and time dilation in a scenario involving three observers: A, B, and C, each moving relative to one another. Proper time for A is derived as t_a=t_c√(1-u²/c²)√(1-v²/c²), while B's proper time is t_b=t_c√(1-u²/c²). The relative velocity of A with respect to C is calculated using the relativistic velocity addition formula, resulting in w=(u+v)/(1+uv/c²). A key point raised is the issue of simultaneity when using time dilation formulas, which can lead to incorrect conclusions if not properly accounted for. The discussion concludes with a suggestion to consider B moving in the opposite direction to clarify the relationships between the observers' time measurements.
QipshaqUli
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Homework Statement
This seemed at first glance very easy. But there appeared some confusion.

A is moving to the right with velocity v with respect to B. The proper time for A is ##t_a=t_b\sqrt{1-v^2/c^2}##. And B is moving to the right with velocity u with respect to C. Proper time for B ##t_b=t_c\sqrt{1-u^2/c^2}##. ##t_a## can be found by ##t_c## then: ##t_a=t_c\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}## then. Futher, by using the law of addition of relativistic velocities one can find the relative velocity of A with respect to C: ##w=\frac{u+v}{1+\frac{uv}{c^2}}##. And defining proper time for A by ##w## I found ##t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}## which is different from previous one.
Relevant Equations
$$t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}$$
Homework Statement: This seemed at first glance very easy. But there appeared some confusion.

A is moving to the right with velocity v with respect to B. The proper time for A is ##t_a=t_b\sqrt{1-v^2/c^2}##. And B is moving to the right with velocity u with respect to C. Proper time for B ##t_b=t_c\sqrt{1-u^2/c^2}##. ##t_a## can be found by ##t_c## then: ##t_a=t_c\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}## then. Futher, by using the law of addition of relativistic velocities one can find the relative velocity of A with respect to C: ##w=\frac{u+v}{1+\frac{uv}{c^2}}##. And defining proper time for A by ##w## I found ##t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}## which is different from previous one.
Homework Equations: $$t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}$$

##t_c## then: ##t_a=t_c\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}##

[Note from mentor: please see https://www.physicsforums.com/help/latexhelp/ for the proper delimiters for LaTeX code on this forum. I have edited your post accordingly, in order to make your equations properly visible.]
 
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You have a problem with the relativity of simultaneity. When you use the time dilation formula for B relative to A you are using the simultaneity of A. Similarly, when you use the time dilation formula for C relative to B you are using the simultaneity in the rest frame of B. Thus, the combination will not correspond to the time dilation of C relative to A, which exclusively is based on simultaneity as defined by A.
 
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QipshaqUli said:
Homework Statement: This seemed at first glance very easy. But there appeared some confusion.

A is moving to the right with velocity v with respect to B. The proper time for A is ##t_a=t_b\sqrt{1-v^2/c^2}##. And B is moving to the right with velocity u with respect to C. Proper time for B ##t_b=t_c\sqrt{1-u^2/c^2}##. ##t_a## can be found by ##t_c## then: ##t_a=t_c\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}## then. Futher, by using the law of addition of relativistic velocities one can find the relative velocity of A with respect to C: ##w=\frac{u+v}{1+\frac{uv}{c^2}}##. And defining proper time for A by ##w## I found ##t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}## which is different from previous one.
Homework Equations: $$t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}$$

Homework Statement: This seemed at first glance very easy. But there appeared some confusion.

A is moving to the right with velocity v with respect to B. The proper time for A is ##t_a=t_b\sqrt{1-v^2/c^2}##. And B is moving to the right with velocity u with respect to C. Proper time for B ##t_b=t_c\sqrt{1-u^2/c^2}##. ##t_a## can be found by ##t_c## then: ##t_a=t_c\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}## then. Futher, by using the law of addition of relativistic velocities one can find the relative velocity of A with respect to C: ##w=\frac{u+v}{1+\frac{uv}{c^2}}##. And defining proper time for A by ##w## I found ##t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}## which is different from previous one.
Homework Equations: $$t_a=t_c\frac{\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}}{1+\frac{uv}{c^2}}$$

##t_c## then: ##t_a=t_c\sqrt{1-u^2/c^2}\sqrt{1-v^2/c^2}##

[Note from mentor: please see https://www.physicsforums.com/help/latexhelp/ for the proper delimiters for LaTeX code on this forum. I have edited your post accordingly, in order to make your equations properly visible.]
Instead, why not have ##B## moving to the left relative to ##C##? The same formulas apply, but now frame ##A## and ##C## are the same frame, yet you have their clocks time dilated relative to each other.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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