<span>Answer:
Yes, I get 17 rad/s², too.
Note that the assumption of constant angular acceleration is really, really, terrible. A valid answer to this question (i.e., one that does not assume constant angular acceleration) involves differential equations. But if you do assume constant angular acceleration, this is quite straightforward. Use constant-acceleration kinematics:
Δθ = ω_i Δt + ½α (Δt)²
You know the pencil moves through an angle of π/2 radians. The initial angular velocity is zero. You already found the angular acceleration, and you want Δt.
Δt = âš[ 2 Δθ / α ] = âš[ 2 (Ď€/2 rad) / 17 rad/s² ] = 0.34 s
This is the same calculation oldprof makes, but his treatment of the pencil as a point mass rather than a uniform rod has thrown his angular acceleration off.</span>
Answer: Larmor suggested in 1919 that a self-exciting dynamo could explain the magnetic field of the earth, as well as that of the sun and other stars, but it was Elsasser and Bullard in the 1940s who showed how motion in the liquid core of the earth might produce a self-sustaining magnetic field. By this time seismology and other studies had given a clearer picture of the earth, as having a solid inner core, a liquid outer core, both with a composition more of metal (mainly iron) than rock, and a rocky mantle, all below a thin crust that is all we can directly see. Energy from radioactivity travels outwards as heat, producing thermal convection in the core. It seems that this convection is the cause of the earth's magnetic field, although our knowledge of the core and its dynamics is sketchy. Our knowledge is limited to saying that flow regimes like those that may be occurring in the core can produce self-sustaining dynamos, with characteristics similar to that needed to produce the earth’s magnetic field.
Explanation:
Answer:
anions
Explanation:
The other are families of the periodic table.
An anion is a negatively charged ion.
Answer:
10 to 15 seconds
Explanation:
because I don't know but rarity is a strong force and it don't take long for a ball to come down
It is the intervention of citizens in decision-making regarding the management of resources and actions that have an impact on the development of their communities.