By examining data from distant stars, astronomers can determine if a star is moving away from or toward Earth. Which of the
following pieces of data would be most helpful in determining
the motion of a star?
A The star gives off blue-white light.
B
The star gives off mainly radio waves and X-rays.
C
The light spectrum given off by the star is shifted toward the
red end.
.
D
The surface temperature of the star is approximately 10,000°
Celsius.

they are all solids.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.

answerto predict;