Answer:
Explanation:
We could use the following suvat equation:
where
s is the vertical displacement of the coin
v is its final velocity, when it hits the water
t is the time
g is the acceleration of gravity
Taking upward as positive direction, in this problem we have:
s = -1.2 m
And the coin reaches the water when
t = 1.3 s
Substituting these data, we can find v:
where the negative sign means the direction is downward.
(a)
The moment of inertia of a uniform-density disk is given by
where
M is the mass of the disk
R is its radius
In this problem,
M = 16 kg is the mass of the disk
R = 0.19 m is the radius
Substituting into the equation, we find
(b) 142.5 J
The rotational kinetic energy of the disk is given by
where
I is the moment of inertia
is the angular velocity
We know that the disk makes one complete rotation in T=0.2 s (so, this is the period). Therefore, its angular velocity is
And so, the rotational kinetic energy is
(c)
The rotational angular momentum of the disk is given by
where
I is the moment of inertia
is the angular velocity
Substituting the values found in the previous parts of the problem, we find