Answer:
a) a = -g = 9.8 m/s² , b) a = 0 m/s² and c) t1 = 0.0213 s
Explanation:
a) At the moment the marble is released its velocity is zero, so it has no resistance force, the only force acting is its weight, so the acceleration is the acceleration of gravity
a = -g = 9.8 m / s²
b) When the marble goes its terminal velocity all forces have been equalized, therefore, the sum of them is zero and consequently if acceleration is also zero
a = 0 m / s²
c) We have to assume a specific type of resistive force, for liquid in general the resistive force is proportional to the speed of the body.
The expression of this situation is
v = mg / b (1 - )
For a very long time the exponential is zero, so the terminal velocity is
= mg / b
b = mg /
b = 5 10-3 9.8 / 0.3
b = 0.163
We already have all the data to calculate the time for v = ½
½ =
(1 -
)
½ = 1- e (- 0.163 t1 / 5 10-3)
e (-32.6 t1) = 1-0.5 (by ln())
-32.6 t1 = ln 0.5
t1 = -1 / 32.6 (-0.693)
t1 = 0.0213 s
Answer: Got It!
<em>Explanation:</em> Guide A Starts From Rest With Pin P At The Lowest Point In The Circular Slot, And Accelerates Upward At A Constant Rate Until It Reaches A Speed Of 175 Mm/s At The ... In the design of a timing mechanism, the motion of pin P in the fixed circular slot is controlled by the guide A, which is being elevated by its lead screw.
Answer:
E) are almost circular, with low eccentricities.
Explanation:
Kepler's laws establish that:
All the planets revolve around the Sun in an elliptic orbit, with the Sun in one of the focus (Kepler's first law).
A planet describes equal areas in equal times (Kepler's second law).
The square of the period of a planet will be proportional to the cube of the semi-major axis of its orbit (Kepler's third law).
Where T is the period of revolution and a is the semi-major axis.
Planets orbit around the Sun in an ellipse with the Sun in one of the focus. Because of that, it is not possible to the Sun to be at the center of the orbit, as the statement on option "C" says.
However, those orbits have low eccentricities (remember that an eccentricity = 0 corresponds to a circle)
In some moments of their orbit, planets will be closer to the Sun (known as perihelion). According with Kepler's second law to complete the same area in the same time, they have to speed up at their perihelion and slow down at their aphelion (point farther from the Sun in their orbit).
Therefore, option A and B can not be true.
In the celestial sphere, the path that the Sun moves in a period of a year is called ecliptic, and planets pass very closely to that path.
Answer:
0.775
Explanation:
The weight of an object on a planet is equal to the gravitational force exerted by the planet on the object:
where
G is the gravitational constant
M is the mass of the planet
m is the mass of the object
R is the radius of the planet
For planet A, the weight of the object is
For planet B,
We also know that the weight of the object on the two planets is the same, so
So we can write
We also know that the mass of planet A is only sixty percent that of planet B, so
Substituting,
Now we can elimanate G, MB and m from the equation, and we get
So the ratio between the radii of the two planets is