1) velocity: 98 m/s downward
Explanation:
The marble moves by uniformly accelerated motion, with constant acceleration a=g=-9.8 m/s^2 directed towards the ground. Therefore, its velocity at time t is given by:
where
is the initial velocity
is the acceleration
is the time
Substituting t = 10 s, we find:
And the negative sign means the direction of the velocity is downward.
2) Distance covered: 490 m
The distance covered in an uniformly accelerated motion can be found with the formula:
where
is the acceleration
t is the time
Substituting t=10 s, we find
And the negative sign means the displacement is below the dropping point.
Atomic mass (z) - atomic number / # of protons (n) = # of neutrons:
151-54=97
You can easily tell what element X is. With an atomic number of 54, the element is the noble gas Xenon (Xe).
<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:
Explanation:
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