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:
D
Explanation:
Gravity is the force of attraction between two objects.
Each object creates a gravitational field in wich every other object is affected by it.
Answer:
Vf = 29.4 m/s
h = 44.1 m
Explanation:
Data:
- Initial Velocity (Vo) = 0 m/s
- Gravity (g) = 9.8 m/s²
- Time (t) = 3 s
- Final Velocity (Vf) = ?
- Height (h) = ?
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Final Velocity
Use formula:
Replace:
Multiply:
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Height
Use formula:
Replace:
Multiply time squared:
Simplify the s², and multiply in the numerator:
It divides:
What is the velocity when falling to the ground?
The final velocity is <u>29.4 meters per seconds.</u>
How high is the building?
The height of the building is <u>44.1 meters.</u>
Answer:
d = 375 m
Explanation:
The speed of sound is constant in any medium, therefore we can use the uniform motion relationships
v = x / t
x = v t
In this case it indicates that the time since the sound is emitted and received is t = 0.50 s, in this time the sound traveled a round trip distance
x = 2d
2d = v t
d = v t/2
let's calculate
d = 1500 0.5 / 2
d = 375 m
The new force would be 1.6 N.
Since the charges multiply as variables (q1)x(q2), then it would simply be double (q1)x(q2), or 1.6.
