does the density of an object appear to change when travelling at relativistic speeds?

Answer 1

Density is the Mass of the object divided by its volume (D=M/V)
At relativistic speed, the mass increases and the length of the object decreases in the direction of travel.
The Density would necessarily have to increase if the Mass increases and the Volume decreases .... i.e. D=>M/

Answer 2

To an observer in the same frame of reference, no
To an observer moving at a relativistic speed, yes. The mass increases and the longitudinal dimension contracts.

Answer 3

The apparent density will change because of two effects: mass increase and Fitzgerald contraction. The apparent length of the object in the direction of travel will be reduced, decreasing the apparent volume.

m = m0 / √[1 - v^2/c^2]

L = L0√[1 - v^2/c^2]

Volume = A*L = A*L0√[1 - v^2/c^2]

Density = m/Volume = m0/L0(1/A)/[1 - v^2/c^2] Rest density = D0 = m0/(L0*A)

Density = D0/[1 - v^2/c^2]

Answer 4

Yes. The mass appears to increase and the volume appears to decrease. So the density appears to increase.

Answer 5

Weather it appears to change is relevant only to the viewer. As an object recedes into the distance it appears smaller in a ratio of distance traversed but its mass is unchanged. On an atomic level the same result is difficult to observe.

Answer 6

As speed increases mass also increase. If mass increases then density increases. At low speeds the effect is very diffucult to measure.