The culture that gave the visiting Europeans eyeglasses and silk fabric was the Chinese civilization. The Chinese invented eyeglasses over a 1,000 years ago<span>, according to British scientist and historian Sir Joseph Needman. By the time Marco Polo arrived in China around 1270, eyeglasses (which he mentions in his accounts) were widely used in Chinese upper class. On the other hand, s</span>ilk has been used by the Chinese for approximately 5,000 years.<span> The earliest evidence of silk dates back to around 4,000-3,000 BC in Shanxi province, where a culture silk cocoon was found.</span>
Answer:
Explanation:
Acceleration is expressed in the following formula:
Where:
is the final velocity of the projectile
is the initial velocity of the projectile
is the time
Solving:
This is the acceleration of the projectile
Answer:
d= 1.56 m
Explanation:
In order to have a constructive interference, the path difference between the sources of the sound, must be equal to an even multiple of the semi-wavelength, as follows:
⇒ d = d₂ - d₁ = 2n*(λ/2)
The minimum possible value for this distance, is when n=1, as it can be seen here:
dmin = λ
In any wave, there exists a fixed relationship between the wave speed, the frequency and the wavelength:
v = λ*f
If v = vsound = 343 m/s, and f = 220 1/s, we can solve for λ:
λ =
⇒ dmin =λ = 1.56 m
Answer:
v = 895 m/s
Explanation:
Time period is given as 39 Earth Days
now the radius of the orbit is given as
so the total path length is given as
now the speed will be given as