# Torque And Rotational Motion

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question
Rank these scenarios on the basis of the linear speed of the block. Rank from largest to smallest. To rank items as equivalent, overlap them. https://session.masteringphysics.com/problemAsset/1011397/40/1011397A.jpg A- R outer=0.4 m, R inner=0.2 m B- R outer=0.6 m, R inner=0.5 m C- R outer=0.6 m, R inner=0.2 m D- R outer=0.8 m, R inner=0.4 m E- R outer=0.2 m, R inner=0.1 m F- R outer=0.4 m, R inner=0.3 m
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Rank the designated points on the basis of their linear or tangential speed. Rank from largest to smallest. To rank items as equivalent, overlap them. https://session.masteringphysics.com/problemAsset/1011397/40/1011397B.jpg A B C D E F
BE, C, AF, D
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Rank the designated points in (Figure 2) on the basis of the magnitude of their linear or radial acceleration. Rank from largest to smallest. To rank items as equivalent, overlap them. https://session.masteringphysics.com/problemAsset/1011397/40/1011397B.jpg A B C D E F
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While the line of children is rotating, which of the following statements are correct? Check all that apply. https://session.masteringphysics.com/problemAsset/1014447/23/1014447.jpg A-The player at the front of the line has the smallest angular acceleration. B-The player at the front of the line has the smallest linear velocity. C-All the children have the same angular acceleration. D-All the children have the same linear velocity.
B, C
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Now consider the children's linear accelerations. Which of the following statements are correct? Check all that apply. A-The last child in the line has the greatest tangential acceleration. B-The last child in the line has the greatest radial acceleration. C-All the children have the same tangential acceleration. D-All the children have the same radial acceleration.
A, B
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A marching band consists of rows of musicians walking in straight, even lines. When a marching band performs in an event, such as a parade, and must round a curve in the road, the musician on the outside of the curve must walk around the curve in the same amount of time as the musician on the inside of the curve. This motion can be approximated by a disk rotating at a constant rate about an axis perpendicular to its plane. In this case, the axis of rotation is at the inside of the curve. Consider two musicians, Alf and Beth. Beth is four times the distance from the inside of the curve as Alf. If Beth travels a distance s during time ?t?tDelta t, how far does Alf travel during the same amount of time? 4s 2s 1/2s 1/4s s
1/4 s
question
A marching band consists of rows of musicians walking in straight, even lines. When a marching band performs in an event, such as a parade, and must round a curve in the road, the musician on the outside of the curve must walk around the curve in the same amount of time as the musician on the inside of the curve. This motion can be approximated by a disk rotating at a constant rate about an axis perpendicular to its plane. In this case, the axis of rotation is at the inside of the curve. If Alf moves with speed vvv, what is Beth's speed? Speed in this case means the magnitude of the linear velocity, not the magnitude of the angular velocity. 4v v 1/4v
4v
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Rank these graphs on the basis of the angular velocity of each object. Rank positive angular velocities as larger than negative angular velocities. Rank from largest to smallest. To rank items as equivalent, overlap them. https://session.masteringphysics.com/problemAsset/1011389/20/1011389.jpg A B C D E F
B,C,AF,DE
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Rank these graphs on the basis of the angular acceleration of the object. Rank positive angular accelerations as larger than negative angular accelerations. Rank from largest to smallest. To rank items as equivalent, overlap them. https://session.masteringphysics.com/problemAsset/1011389/20/1011389.jpg A B C D E F
They are all equal
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As you finish listening to your favorite compact disc (CD), the CD in the player slows down to a stop. Assume that the CD spins down with a constant angular acceleration. If the CD rotates clockwise at 500 rpmrpm (revolutions per minute) while the last song is playing, and then spins down to zero angular speed in 2.60 ss with constant angular acceleration, what is ??alpha, the magnitude of the angular acceleration of the CD, as it spins to a stop? Express your answer in radians per second squared.
question
As you finish listening to your favorite compact disc (CD), the CD in the player slows down to a stop. Assume that the CD spins down with a constant angular acceleration. How many revolutions does the CD make as it spins to a stop? Express your answer using three significant figures.
10.8 revolutions
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Rank in order, from smallest to largest, the torques ?1 to ?4 about the centers of the circles. To rank items as equivalent, overlap them. https://session.masteringphysics.com/problemAsset/1810494/3/jfk.Figure.P07.05.jpg 1 2 3 4
1, 23, 4
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Rank these forces (A through F) on the basis of the magnitude of the torque they apply to the wrench, measured about an axis centered on the bolt. Rank from largest to smallest. To rank items as equivalent, overlap them. https://session.masteringphysics.com/problemAsset/1013190/20/1013190A.jpg A B C D E F
D, BE, F, A, C
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What is the moment of inertia I of this assembly about the axis through which it is pivoted? Express the moment of inertia in terms of mr, m1, m2, and x. Keep in mind that the length of the rod is 2x, not x. https://session.masteringphysics.com/problemAsset/1011170/19/MRB_mi_6.jpg
x^2(m1+m2+1/3mr)
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Suppose that the rod is held at rest horizontally and then released. (Throughout the remainder of this problem, your answer may include the symbol III, the moment of inertia of the assembly, whether or not you have answered the first part correctly.) What is the angular acceleration ??alpha of the rod immediately after it is released? Take the counterclockwise direction to be positive. Express ??alpha in terms of some or all of the variables mr, m1, m2, x, I, and g. https://session.masteringphysics.com/problemAsset/1011170/19/MRB_mi_6.jpg
((m1?m2)gx)/I
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If the sphere on the left is moved closer to the central cylinder and placed at a distance R/2R/2 from the axis of rotation, what is the magnitude of the angular acceleration ??alpha of the modified system? Assume that the rest of the system doesn't change. https://session.masteringphysics.com/problemAsset/1014246/17/1014246A.jpg ?=rF/3mR2 ?=3rF/2mR2 ?=2rF/3mR2 ?=rF/2mR2
a=2rF/3mR2
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In this problem, you will practice applying this formula to several situations involving angular acceleration. In all of these situations, two objects of masses m1m1m_1 and m2m2m_2 are attached to a seesaw. The seesaw is made of a bar that has length lll and is pivoted so that it is free to rotate in the vertical plane without friction.Assume that the pivot is attached to the center of the bar. You are to find the angular acceleration of the seesaw when it is set in motion from the horizontal position. In all cases, assume that m1>m2m1>m2. https://session.masteringphysics.com/problemAsset/1016276/11/1016276A.jpg Assume that the mass of the swing bar, as shown in the figure, is negligible.(Figure 1) Find the magnitude of the angular acceleration ??alpha of the seesaw. Express your answer in terms of some or all of the quantities m1, m2, l, as well as the acceleration due to gravity g.
? =2(m1?m2/m1+m2)g/l
question
In this problem, you will practice applying this formula to several situations involving angular acceleration. In all of these situations, two objects of masses m1m1m_1 and m2m2m_2 are attached to a seesaw. The seesaw is made of a bar that has length lll and is pivoted so that it is free to rotate in the vertical plane without friction.Assume that the pivot is attached to the center of the bar. You are to find the angular acceleration of the seesaw when it is set in motion from the horizontal position. In all cases, assume that m1>m2m1>m2. In what direction will the seesaw rotate, and what will the sign of the angular acceleration be? https://session.masteringphysics.com/problemAsset/1016276/11/1016276A.jpg ? =2(m1?m2/m1+m2)g/l A-The rotation is in the clockwise direction and the angular acceleration is positive. B-The rotation is in the clockwise direction and the angular acceleration is negative. C-The rotation is in the counterclockwise direction and the angular acceleration is positive. D-The rotation is in the counterclockwise direction and the angular acceleration is negative.
C
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In this problem, you will practice applying this formula to several situations involving angular acceleration. In all of these situations, two objects of masses m1m1m_1 and m2m2m_2 are attached to a seesaw. The seesaw is made of a bar that has length lll and is pivoted so that it is free to rotate in the vertical plane without friction.Assume that the pivot is attached to the center of the bar. You are to find the angular acceleration of the seesaw when it is set in motion from the horizontal position. In all cases, assume that m1>m2m1>m2. Now consider a similar situation, except that now the swing bar itself has mass mbarmbarm_bar.(Figure 2) Find the magnitude of the angular acceleration ??alpha of the seesaw. Express your answer in terms of some or all of the quantities m1m1m_1, m2m2m_2, mbarmbarm_bar, lll, as well as the acceleration due to gravity ggg. https://session.masteringphysics.com/problemAsset/1016276/11/1016276A.jpg
a=6g(m1?m2)/(3(m1+m2)+mbar)l
question
In this problem, you will practice applying this formula to several situations involving angular acceleration. In all of these situations, two objects of masses m1m1m_1 and m2m2m_2 are attached to a seesaw. The seesaw is made of a bar that has length lll and is pivoted so that it is free to rotate in the vertical plane without friction.Assume that the pivot is attached to the center of the bar. You are to find the angular acceleration of the seesaw when it is set in motion from the horizontal position. In all cases, assume that m1>m2m1>m2. In what direction will the seesaw rotate, and what will the sign of the angular acceleration be? https://session.masteringphysics.com/problemAsset/1016276/11/1016276A.jpg a=6g(m1?m2)/(3(m1+m2)+mbar)l A-The rotation is in the clockwise direction and the angular acceleration is positive. B-The rotation is in the clockwise direction and the angular acceleration is negative. C-The rotation is in the counterclockwise direction and the angular acceleration is positive. D-The rotation is in the counterclockwise direction and the angular acceleration is negative.
C
question
When a rigid object rotates about a fixed axis, what is true about all the points in the object? (There could be more than one correct choice.) Check all that apply. They all have the same angular speed. They all have the same tangential acceleration. They all have the same angular acceleration. They all have the same tangential speed. They all have the same radial acceleration.
They all have the same angular acceleration. They all have the same angular speed.
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The figure shows scale drawings of four objects, each of the same mass and uniform thickness, with the mass distributed uniformly. Which one has the greatest moment of inertia when rotated about an axis perpendicular to the plane of the drawing at point P? https://session.masteringphysics.com/problemAsset/1901533/2/8514108001.jpg A B C D The moment of inertia is the same for all of these objects.
B
question
As shown in the figure, a given force is applied to a rod in several different ways. In which case is the torque about the pivot P due to this force the greatest? https://session.masteringphysics.com/problemAsset/1901536/2/8514108003.jpg 1 2 3 4 5
1
question
Five forces act on a rod that is free to pivot at point P, as shown in the figure. Which of these forces is producing a counter-clockwise torque about point P? (There could be more than one correct choice.) https://session.masteringphysics.com/problemAsset/1901537/4/8514108004.jpg force A force B force C force D force E
force C
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The rotating systems shown in the figure differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). If you release the hanging blocks simultaneously from rest, https://session.masteringphysics.com/problemAsset/1901538/2/8514108005.jpg the block at the right lands first. both blocks land at the same time. the block at the left lands first.
the block at the right lands first.
question
While working on her bike, Amanita turns it upside down and gives the front wheel a counterclockwise spin. It spins at approximately constant speed for a few seconds. During this portion of the motion, she records the x and y positions and velocities, as well as the angular position and angular velocity, for the point on the rim designated by the yellow-orange dot in the figure. (Figure 1) Let the origin of the coordinate system be at the center of the wheel, the positive x direction to the right, the positive y position up, and the positive angular position counterclockwise. The graphs(Figure 2) begin when the point is at the indicated position. One graph may be the correct answer to more than one part. Which of the graphs corresponds to x position versus time? https://session.masteringphysics.com/problemAsset/1011381/26/1011381B.jpg