Answer:
a) See Below
b) See Below
c) See Below
Step-by-step explanation:
The relative solidification time is given by formula 
Where C_m is the Chvorinov's constant given as 3.5
V is Volume
A is Surface Area
a)
<u>Sphere:</u>
Volume = 
Surface Area = 
Now putting in the formula:
Relative Solidification Time of Sphere =
minutes
Relatively, We can say t_s = 2.778 * C_m
<u>Cube:</u>
Volume = 10^3 = 1000
Surface Area = 6x^2 = 6(10)^2 = 600
Relative Solidification Time of Cube =
minutes
Relatively, We can say t_s = 2.778 * C_m
<u>Cylinder:</u>
Volume = 
Surface Area = 
Relative Solidification Time of Cylinder = 
Relatively, We can say t_s = 2.778 * C_m
b)
All of them have same relative solidification time. So we can say that all 3 of them are good for making risers.
c)
Since, we had
Relatively, We can say t_s = 2.778 * C_m
we get:
t_s = 2.778 * C_m = 2.778 * 3.5 = 9.72 minutes