In what may be one of the most remarkable coincidences in
all of physical science, the tangential component of circular
motion points along the tangent to the circle at every point.
The object on a circular path is moving in that exact direction
at the instant when it is located at that point in the circle. The
centripetal force ... pointing toward the center of the circle ...
is the force that bends the path of the object away from a straight
line, toward the next point on the circle. If the centripetal force
were to suddenly disappear, the object would continue moving
from that point in a straight line, along the tangent and away from
the circle.
The Pony Express
Chapter 1
At A Nation's Crisis
The Pony Express was the first rapid transit and the first fost mail line across the continent from the Missouri River to the Pacific Coast. It was a system
by means of which messages were carried swiftly on horseback across the plains and deserts, and over the mountains of the far West It brought the
Adontic coost and the Pacific slope ten days nearer to each other.
It had a brief existence of only sixteen months and was supplanted by the transcontinental telegraph. Yet it was of the greatest importance in
binding the East and West together at a time when overland travel was slow and cumbersome, and when a great national crisis made the rapid
communication of news between these sections an imperative necessity.
The Pony Express marked the highest development in overland travel prior to the coming of the Pacific railroad, which it preceded nine years.
It, in fact, proved the feasibility of a transcontinental road and demonstrated that such a line could be built and operated continuously the year
around-a feat that had always been regarded as impossible.
The operation of the Pony Express was a supreme achievement of physical endurance on the part of man and his ever faithful companion, the
horse. The history of this organization should be a lasting monument to the physical sacrifice of man and beast in an effort to accomplish
something worthwhile. Its history should be an enduring tribute to American courage and American organizing genius.
Read this line from the Pony Express excerpt
It hod a brief existence of only sixteen months and was supplanted by the transcontinental telegraph.
Based on the corres, what does the word "supplanted" mean? (5 points)
Defeated
Joined
Replaced
Os
Oo
Unearthed
Answer:
8.3m/s
Explanation:
Given parameters:
mass of clay ball = 5kg
Speed of clay ball = 25m/s
mass of clay ball at rest = 10kg
speed of clay ball at rest = 0m/s
Unknown:
Velocity after collision = ?
Solution:
Since the balls stick together, this is an inelastic collision:
m1v1 + m2v2 = v(m1 + m2)
5(25) + 10(0) = v (5 + 10)
125 = 15v
v = 8.3m/s
Answer:
96.21 ft/s
Explanation:
To solve this, you only need to use one expression which is:
Vf² = Vo² + 2gh
g = 9.8 m/s²
However, this exercise is talking in feet, so convert the gravity to feet first:
g = 9.8 * 3.28 = 32.15 ft/s²
Vo is zero, because it's a free fall and in free fall the innitial speed is always zero. With this, let's calculate the speed at 2 seconds, with a height of 64 ft, and then with the 256 ft:
V1 = √2*32.15*64
V1 = 64.15 ft/s
V2 = √2*32.15*256
V2 = 128.3 ft/s
So the average rate is:
V = 128.3 + 64.15 / 2
V = 96.22 ft/s