Class Management i Help Practice Problems 11: Center of Mass, Conservation Begin
ID: 1446901 • Letter: C
Question
Class Management i Help Practice Problems 11: Center of Mass, Conservation Begin Date: 3/6/2016 12:00:00 AM Due Date: 5/8/2016 12:00:00 AM End Date: 5/8/2016 12:00:00 AM (13%) Problem 3: A uniform circular disk of radius R 38 cm has a hole cut out of it with radius r 19 cm. The edge of the hole touches the center of the circular disk. The disk has uniform area density o Randomized Variables R 38 cm. r 19 cm Otheexpertta.com 20% Part (a) The vertical center of mass of the disk with hole will be located F 20% Part (b) The horizontal center of mass of the disk with hole will be located 20% Part (c) Write a symbolic equation for the total mass of the disk with the hole 20% Part (d) Write an equation for the horizontal center of mass of the disk with the hole as measured from the center of the disk Grade Summary Deductions 4% Cnn Potential 96% 7 8 9 Submissions Attempts remaining 4 5 6 4% per attempt) detailed view 2 3 4% Hint Feedback Submit I give up! deduction per hint. Hints remaining: Feedback 5% deduction per feedback. Hints: 4% A 20% Part (e) Calculate the numeric position of the center of mass of the disk with hole from the center of the disk in cmExplanation / Answer
a) about x axis passing through the centre disc is symmetric.
hence Ycm = 0
d) Lets assume this system as one complete disc of radius R with density rho and one
small disc of radius r of density -ve rho.
adding these two disc we will get this given disc.
Xcm = ( m1x1 + m2x2 ) / (m1 + m2)
Xcm = [ ( pi r^2 (-r) (-rho) ) + (pi R^2 rho x 0 )] / ( pi r^2 (-rho) + pi R^2 (rho))
Xcm = r^3 / (R^2 - r^2)
e) Xcm = (0.19^3) / (0.38^2 - 0.19^2)
Xcm = 0.0633 m = 6.33 cm