Mechanics | Relativity Answers

An elevator starts from rest with a constant upward acceleration and moves 1 m in the first 1.9 s. A passenger in the elevator is holding a 5 kg bundle at the end of a vertical cord.
What is the tension in the cord as the ele- vator accelerates? The acceleration of gravity is 9.8 m/s2 .
Answer in units of N

I'm not asking you without trying to slove it myself, here's the quetion 1st:

If the three quantities; mass, diameter, and height for a cylinder are measured with the same percentage error, which would contribute the most to the error in the density?

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so, I tried to answer it like this:
since the equation for the cylinder density is p=2*M/(pi*d^2*h)
since the mass and the height aren't squared the error would remain the same, however the diameter is squared which means the error is squared as well.. so it's the diameter!!!!

BUT my friend says since p(density)=M/V , then mass would contribute the most not diameter ;O

HELP PLEASE , I dont know which answer to put in our report D:?!

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