Question

1. record the following parameters during the process: name each material (parts and final) a) methylphenyl disocyanate b) benzene homopolymer mass of each material component 14.7g a 47.5g b mold internal diameter 3.186in³ mix time 25 secs mold time and external temperature 12 min 70°f ball temperature at demold 78°f mass of the ball 40.4g ball’s final diameter 3.222in³ 6. identify the chemical names for part a and part b. 7. list three advantages and three disadvantages of foamed vs. non - foamed plastics. 8. calculate the weight (lbr), specific weight (lbr/ft³) and density (g/mm³) of the foam used to make your group’s polyurethane ball from your equations based on measured diameter and mass. show all calculation steps. (calculations may be written on the opposite side of this paper or on another sheet, as needed). weight of ball: ________lbr specific weight of foam: ______lbr/ft³ density of foam: ________g/mm³

Explanation:

Step1: Convert mass to weight

The weight $W$ in pounds - force ($lbf$) is given by $W = mg$, where $m$ is the mass and $g$ is the acceleration due to gravity. On Earth, $g= 32.2\ ft/s^{2}$. First, convert the mass of the ball from grams to slugs. Since $1\ slug = 32.174\ lb_{m}$ and $1\ g=0.00220462\ lb_{m}$, the mass of the ball $m = 40.4\ g=40.4\times0.00220462\ lb_{m}=0.0890666\ lb_{m}$. Then, $W=\frac{m\times g}{32.2\ ft/s^{2}}$. Substituting $m = 0.0890666\ lb_{m}$ and $g = 32.2\ ft/s^{2}$, we get $W=\frac{0.0890666\times32.2}{32.2}=0.0890666\ lbf$.

Step2: Calculate the volume of the ball

The ball is spherical, and the volume of a sphere is $V=\frac{4}{3}\pi r^{3}$, where $r$ is the radius. Given the diameter $d = 3.222\ in$, so $r=\frac{d}{2}=\frac{3.222}{2}=1.611\ in$. Convert the radius to feet: $r = 1.611\ in\times\frac{1}{12}\ ft/in=0.13425\ ft$. Then $V=\frac{4}{3}\pi(0.13425)^{3}\ ft^{3}\approx0.01027\ ft^{3}$.

Step3: Calculate specific - weight

The specific - weight $\gamma$ is given by $\gamma=\frac{W}{V}$. Substituting $W = 0.0890666\ lbf$ and $V = 0.01027\ ft^{3}$, we get $\gamma=\frac{0.0890666}{0.01027}\ lbf/ft^{3}\approx8.67\ lbf/ft^{3}$.

Step4: Convert volume to $mm^{3}$ and mass to $g$ for density calculation

The volume $V$ in $mm^{3}$: First, convert the volume from $in^{3}$ to $mm^{3}$. Since $1\ in = 25.4\ mm$, $V=\frac{4}{3}\pi(\frac{3.222\times25.4}{2})^{3}\ mm^{3}\approx172097.7\ mm^{3}$. The mass of the ball $m = 40.4\ g$. The density $
ho$ is given by $
ho=\frac{m}{V}$. Substituting $m = 40.4\ g$ and $V = 172097.7\ mm^{3}$, we get $
ho=\frac{40.4}{172097.7}\ g/mm^{3}\approx0.000235\ g/mm^{3}$.

Answer:

Weight of ball: $0.0890666\ lbf$
Specific weight of foam: $8.67\ lbf/ft^{3}$
Density of foam: $0.000235\ g/mm^{3}$