Answer:
Milimeters
Explanation:
This kind of question must be checked with everyday elements, in this way we will analyze each of the options until we reach the appropriate:
kilograms can not be because this unit serves to measure the mass not the length.
kilometers (km) is a unit of length, but however it does not serve for this measurement since a km is equivalent to 1000 meters, therefore measuring the length of a shoe with a ruler measuring 1000 meters is very impractical.
milliliters is a unit of volume, and can often be found in the measurement of volume content of liquids, for example 700 milliliters of milk or 1000 milliliters of water. Therefore it is impractical to measure a shoe with a unit of volume.
In this way the way to measure a shoe correctly is using a ruler or measuring instrument graduated in millimeters.
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
.
The correct answer for the question that is being presented above is this one: "B. 13m."
The formula of wave velocity is this:
wave velocity = f * <span>λ
</span>λ = v / f
<span>λ</span> = 343m/s / 26Hz
λ = 13.20m .. ans (b)
Here are the following choices:
A. 5m
B. 13m
C. 28m
D. 58m
Answer: Well the kinetic energy decreasesTherefore, the thermal energy of an object decreasesas its temperature decreases.