If you guys would be kind enough to show me if my attempt to problems posted are correct or incorrect.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

A uniform 3.0 kg cylinder of radius 0.15 m is suspended by two strings wrapped around it, as shown in the figure below. As the cylinder descends, the strings unwind from it. What is the acceleration of the center of mass of the cylinder? (Neglect the mass of the string.)

http://www.webassign.net/wb/8-43.gif

2. Relevant equations

α = alpha

rmg = ½mr²

a = rα

3. The attempt at a solution

2g = rα

2g/r = α

Once I know α, I can plug into a = rα

and my answer is19.6 m/s²

. The problem statement, all variables and given/known data

In the figure below, a constant horizontal force Fapp of magnitude 15 N is applied to a wheel of mass 9 kg and radius 0.70 m. The wheel rolls smoothly on the horizontal surface, and the acceleration of its center of mass has magnitude 0.67 m/s2.

http://www.webassign.net/hrw/hrw7_11-30.gif

a)In unit-vector notation, what is the frictional force on the wheel?

b) What is the rotational inertia of the wheel about the rotation axis through its center of mass?

2. Relevant equations

ma-F =Ffriction

T =Iα

α = a/r

3. The attempt at a solution

a) ma- F = Ffriction

(9kg)(0.67m/s²) - 15 N =8.97 N

b) T =Iα

(Ffrictional)(r) = (I)(a/r)

(Ffrictional)(r²)/(a) = I

6.56kg m² = I

1. The problem statement, all variables and given/known data

The body in the figure is pivoted at O. Three forces act on it in the directions shown on the figure. FA = 12 N at point A, 8.0 m from O. FB = 16 N at point B, 4.0 m from O. FC = 19 N at point C, 3.0 m from O. What is the net torque about O?

http://www.webassign.net/hrw/11_39.gif

2. Relevant equations

T = r F sinФ

3. The attempt at a solution

TA = (8m)(12N)(sin45) = 67.88 N m

TB = (4m)(16N)(sin90) = 64 N m

TC = (3m)(19N)(sin20) = 19.50 nm

Tnet = 151.38 N m

1. The problem statement, all variables and given/known data

(a) How many uniform, identical textbooks of width 30.0 cm can be stacked on top of each other on a level surface without the stack falling over if each successive book is displaced 2.50 cm in width relative to the book below it?

(b) If the books are 5.00 cm thick, what will be the height of the center of mass of the stack above the level surface?

3. The attempt at a solution

There is no equation for me to solve.. I just did this problem by attempting to find the Center of Mass for the books as it stacks up. By drawing out a picture, I found that the for part a) it would take a total of7 books.

b) If there are 7 books total, the stack center of mass would be 3.5 cm. Finally, take the center of mass(3.5cm) and multiply by the thickness(5.0cm) of each book to find the height.17.5cm

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# Homework Help: What is the acceleration of the center of mass of the cylinder?

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