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cloudzer0
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If you guys would be kind enough to show me if my attempt to problems posted are correct or incorrect.
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
α = alpha
rmg = ½mr²
a = rα
2g = rα
2g/r = α
Once I know α, I can plug into a = rα
and my answer is 19.6 m/s²
. Homework Statement
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?
ma-F =Ffriction
T =Iα
α = a/r
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
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
T = r F sinФ
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
(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?
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 of 7 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
Homework Statement
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
Homework Equations
α = alpha
rmg = ½mr²
a = rα
The Attempt at a Solution
2g = rα
2g/r = α
Once I know α, I can plug into a = rα
and my answer is 19.6 m/s²
. Homework Statement
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?
Homework Equations
ma-F =Ffriction
T =Iα
α = a/r
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
Homework Statement
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
Homework Equations
T = r F sinФ
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
Homework Statement
(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?
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 of 7 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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