CCE 170 - Exam #1 KEY

Fall Semester 2021

19. (excel) The terminal velocity of a falling object attached to a parachute can be computed using the following equation:

where:

	=	gravitational constant
	=	total mass = mass of the object plus the mass of the parachute
	=
	=	density of the parachute
	=	area of the parachute =
	=	drag coefficient
	=	density of air

The following spreadsheet is designed to compute the terminal velocity for parachutes under a variety of conditions:

Click here to download a copy of the spreadsheet. 

Click here to download a copy of the solution.

Do NOT use any named cells for this spreadsheet!

a. (2 pts) Use Data Validation to associate cell B4 with the two values in S4:S5. In other words, the user should only be able to enter "SI" or "FSS" in cell B4.

b. (3 pts) Enter a formula for cell C5 that automatically displays "[m/sec^2]" if the units are SI and "[ft/sec^2]" if the units are FSS.

c. (1.5 pts) Enter a formula for the area of the parachute in B12:B21.  Enter the formula is cell B12 and then copy it to the remaining cells.

d. (1.5 pts) Enter a formula for the total mass in C12:C21.  Enter the formula is cell C12 and then copy it to the remaining cells.

e. (3 pts) Enter a formula for the terminal velocity in D12:D21.  Enter the formula is cell D12 and then copy it to the remaining cells. 

f. (2 pts) Copy the formulas of row 21 to row 24. Then use Goal Seek tool to find the radius of parachute required to lower a 500 kg object at a terminal velocity of exactly 15 m/s. I.e., set m_o in cell B9 to 500 and use the equations you copied to row 24 to solve for the proper radius.

g. (3 pts) Create an xy scatter plot showing vt (y axis) vs. radius of parachute (x axis) using the main part of your table (rows 12 through 21). Add a set of titles and remove the legend. This plot should only include one y series (vt).

(Upload instructions and links went here)