When you touch an object and heat flows OUT of it, INTO your finger, you say the object feels hot.
When you touch an object and heat flows INTO it, OUT of your finger, you say the object feels cold.
If the object has the same temperature as your finger ... <em>around the mid-90s</em> ... then no heat flows in or out of your finger when you touch the object, and the object doesn't feel hot or cold.
Answer:
at the speed of light (
)
Explanation:
The second postulate of the theory of the special relativity from Einstein states that:
"The speed of light in free space has the same value c in all inertial frames of reference, where
"
This means that it doesn't matter if the observer is moving or not relative to the source of ligth: he will always observe light moving at the same speed, c.
In this problem, we have a starship emitting a laser beam (which is an electromagnetic wave, so it travels at the speed of light). The startship is moving relative to the Earth with a speed of 2.0*10^8 m/s: however, this is irrelevant for the exercise, because according to the postulate we mentioned above, an observer on Earth will observe the laser beam approaching Earth with a speed of
.