How Does Velocity Affect Mass in Relativity?

AI Thread Summary
In the discussion about how velocity affects mass in relativity, a problem is presented where a man weighing 78 kg on Earth is considered on a starship traveling at 0.93c. The formulas for relativistic mass change are discussed, specifically M = Mo / √(1 - v^2/c^2). Using this formula, the calculated relativistic mass is approximately 212.2 kg. The conversation confirms the distinction between weight and mass, emphasizing that the problem states weight, but the solution focuses on mass. The final answer of 212.2 kg is presented as the correct working.
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Homework Statement



On Earth a man weights 78kg. what is his weight on a starship which is traveling at 0.93c?


Homework Equations



Are the following correct for mass change in terms of relativity?

mr = E/c2
m0 = sqrt(E2/c4 - p2/c2)

Where E is energy, p is momentum and c is the speed of light in vacuum

Need help solving this!
Thank you in advance!
 
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Are you sure the problem is stated as weight? Because, if it is, then the solution is pretty simple...

If it says "mass", then we can do more... :)
 
yes it states weight and i think i have an idea of how to do it using the formula
M= Mo / [√ 1 - v^2/ c^2]
where Mo is 78kg and velocity is 0.93c
M= 78 / [√ 1 - (0.93c^2)^2/ c^2]
M= 78 / [√ 1 - 0.93c^2]
M=212.2105291kg

So the weight would be approximately 212.2 kg

is this correct working and answer?

thank you in advance~!

s
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
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Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
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