KE = (1/2)·(mass)·(speed)²
KE = (1/2)·(50 kg)·(18 m/s)²
KE = (25 kg)·(324 m²/s²)
KE = 8,100 kg-m²/s²
KE = 8,100 Joules
(a) is a decomposition reaction
To solve this problem we will start from the given concept in which the number of turns is equivalent to the length of the thread per circumference of spool. That is:

Where,
l = length of the thread
= circumference of spool
For \phi we have that,

For l we have that
l = 62.8m
Finally the number of Turns would be,



Therefore the number of turns of thread on the spool are 1000turns.
Answer:
Fc = 1.7x10^-4 N
Explanation:
Convert everything to proper units:
m = 25mg = 2.5x10^-5 kg
r = 17.6cm = 0.176m
v = 110cm/s = 1.1m/s
the formula for centripetal force is Fc = mv^2 / r
Plug everything and solve for Fc;
fc = (2.5x10^-5)(1.1^2) / 0.176
Fc = 1.7x10^-4 N