Answer:
b. v = 0, a = 9.8 m/s² down.
Explanation:
Hi there!
The acceleration of gravity is always directed to the ground (down) and, near the surface of the earth, has a constant value of 9.8 m/s². Since the answer "b" is the only option with an acceleration of 9.8 m/s² directed downwards, that would solve the exercise. But why is the velocity zero at the highest point?
Let´s take a look at the height function:
h(t) = h0 + v0 · t + 1/2 g · t²
Where
h0 = initial height
v0 = initial velocity
t = time
g = acceleration due to gravity
Notice that the function is a negative parabola if we consider downward as negative (in that case "g" would be negative). Then, the function has a maximum (the highest point) at the vertex of the parabola. At the maximum point, the slope of the tangent line to the function is zero, because the tangent line is horizontal at a maximum point. The slope of the tangent line to the function is the rate of change of height with respect to time, i.e, the velocity. Then, the velocity is zero at the maximum height.
Another way to see it (without calculus):
When the ball is going up, the velocity vector points up and the velocity is positive. After reaching the maximum height, the velocity vector points down and is negative (the ball starts to fall). At the maximum height, the velocity vector changed its direction from positive to negative, then at that point, the velocity vector has to be zero.
Answer:
elastic force and weight are related to the acceleration of the System.
Explanation:
The relationship between these two forces can be found with Newton's second law.
- W = m a
K x - m g = m a
We see that elastic force and weight are related to the acceleration of the System.
If a harmonic movement is desired, an extra force that increases the elastic force is applied, but to begin the movement this force is eliminated, in general , if the relationship between this external and elastic force is desired, the only requirement is that it be small for harmonic movement to occur
Answer:
Explanation:
The force on the point charge q exerted by the rod can be found by Coulomb's Law.
Unfortunately, Coulomb's Law is valid for points charges only, and the rod is not a point charge.
In this case, we have to choose an infinitesimal portion on the rod, which is basically a point, and calculate the force exerted by this point, then integrate this small force (dF) over the entire rod.
We will choose an infinitesimal portion from a distance 'x' from the origin, and the length of this portion will be denoted as 'dx'. The charge of this small portion will be 'dq'.
Applying Coulomb's Law:
The direction of the force on 'q' is to the right, since both charges are positive, and they repel each other.
Now, we have to write 'dq' in term of the known quantities.
Now, substitute this into 'dF':
Now we can integrate dF over the rod.
Answer:
Cable color codes are very important for example, If something is not wired properly, it can result in injuries, deaths, fires, and many other problems. This is why there are well-established wire color codes to ensure those working with an around this type of equipment can ensure everything is wired safely and effectively. If we used three phase cables without color code, this can lead too incorrect things that might be a hazard too get not fix and learning new color codes would be hard therefore we should stick too the same color codes for cables and it saves the hassle for needing too check every cable cord color then the original one signed too it.
The scientists describe them as D. Elliptical
