Ehimay

University M

## Wall

wrote the 15/07/2012 10:34

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Ehimay hasn't written any article yet## Questions

## 1

Answers#### "A disk is free to rotate on afixed axis. A force of given magnitudeF, in the plane of the disk, is to be applied. Of the following alternatives the greatest angular acceleration is obtained if the force is:"

"
A. applied tangentially halfway between the axis and the rim
B. applied tangentially at the rim
C. applied radially halfway between the axis and the rim
D. applied radially at the rim
E. applied at the rim but neither radially nor tangentially"

26/02/2013
## 1

Answers#### "τ=Iα for an object rotating about a fixed axis, whereτis the net torque acting on it, Iis its rotational inertia, andαis its angular acceleration. This expression:"

"
A. is the definition of torque
B. is the definition of rotational inertia
C. is the definition of angular acceleration
D. follows directly from Newton’s second law
E. depends on a principle of physics that is unrelated to Newton’s second law"

26/02/2013
## 1

Answers#### A force with a given magnitude is to be applied to a wheel. The torque can be maximized by:

"
A. applying the force near the axle, radially outward from the axle
B. applying the force near the rim, radially outward from the axle
C. applying the force near the axle, parallel to a tangent to the wheel
D. applying the force at the rim, tangent to the rim
E. applying the force at the rim, at 45
to the tangent"

26/02/2013
## 1

Answers#### "The rotational inertia of a disk about its axis is 0.70kg·m2 . When a 2.0-kg weight is added to its rim, 0.40m from the axis, the rotational inertia becomes:"

"
A. 0.38kg·m2
B. 0.54kg·m2
C. 0.70kg·m2
D. 0.86kg·m2
E. 1.0kg·m2"

26/02/2013
## 1

Answers#### To increase the rotational inertia of a solid disk about its axis without changing its mass:

"
A. drill holes near the rim and put the material near the axis
B. drill holes near the axis and put the material near the rim
C. drill holes at points on a circle near the rim and put the material at points between the
holes
D. drill holes at points on a circle near the axis and put the material at points between the
holes
E. do none of the above (the rotational inertia cannot be changed without changing the mass)"

26/02/2013
## 1

Answers#### "A uniform solid cylinder made of lead has the same mass and the same length as a uniform solid cylinder made of wood. The rotational inertia of the lead cylinder compared to the wooden one is: "

"A. greater
B. less
C. same
D. unknown unless the radii are given
E. unknown unless both the masses and the radii are given"

26/02/2013
## 1

Answers#### "Two uniform circular disks having the same mass and the same thickness are made from different materials. The disk with the smaller rotational inertia is:"

"
A. the one made from the more dense material
B. the one made from the less dense material
C. neither – both rotational inertias are the same
D. the disk with the larger angular velocity
E. the disk with the larger torque"

26/02/2013
## 1

Answers#### "Consider four objects, each having the same mass and the same radius: 1. a solid sphere 2. a hollow sphere 3. aflat disk in thex,yplane 4. a hoop in thex,yplane The order of increasing rotational inertia about an axis through the center of mass and parallel to thezaxis is:"

"A. 1, 2, 3, 4
B. 4, 3, 2, 1
C. 1, 3, 2, 4
D. 4, 2, 3, 1
E. 3, 1, 2, 4"

26/02/2013
## 1

Answers#### The rotational inertia of a wheel about its axle does not depend upon its:

"
A. diameter
B. mass
C. distribution of mass
D. speed of rotation
E. material composition"

26/02/2013
## 1

Answers#### "The magnitude of the acceleration of a point on a spinning wheel is increased by a factor of 4 if:"

"
A. the magnitudes of the angular velocity and the angular acceleration are each multiplied by
a factor of 4
B. the magnitude of the angular velocity is multiplied by a factor of 4 and the angular accel-eration is not changed
C. the magnitudes of the angular velocity and the angular acceleration are each multiplied by
a factor of 2
D. the magnitude of the angular velocity is multiplied by a factor of 2 and the angular accel-eration is not changed
E. the magnitude of the angular velocity is multiplied by a factor of 2 and the magnitude of
the angular acceleration is multiplied by a factor of 4"

26/02/2013
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