Daniel B. answered 04/05/21
A retired computer professional to teach math, physics
Let
g be the gravitation acceleration (known),
M be the mass of the bucket (assumed given),
m be the mass of the reel (assumed given),
r be the radius of the reel (assumed given),
a be the acceleration of the bucket (to be calculated),
T be the tension in the string (to be calculated),
I = mr²/2 be the moment of inertia of the reel.
a.
There is one force acting on the reel -- the downward tension T.
There are two forces acting on the bucket --
downward weight Mg, and
upward tension T.
b.
Reel:
Ia/r = Tr (Moment of inertial x angular acceleration = torque)
amr/2 = Tr (After substituting I into the above)
Bucket:
Ma = Mg - T (Mass x acceleration = force)
c. and d.
T = am/2 (From the equation for the reel)
Ma = Mg - am/2 (After substituting T into the equation for the bucket)
a = gM/(M+m/2) (Solving for a)
T = gMm/(2M+m) (Substituting a into solution for T)
e.
Let t = 3s be the time the bucket falls.
From definition of acceleration the distance is
at²/2 = 9gM/(2M+m)