Question

A
computer hard disk starts from rest, then speeds up with an angular
acceleration of 210 rad/ s^2 for 5.0 s until it reaches its final
angular speed. It rotates for another 6.0 s at that constant
angular speed. It then slows down and comes to rest in 9.0 s.

A. determine the angular speed of the disk 5.0 s after start
up. Express your answer in rad/s and rpm (rev/min).

B. determine the angular speed of the disk 11.0 s after start
up.

C. determine the angular acceleration of the disk when it was
slowing down.

D. determine the number of revolutions made by the disk in the
20 s it was spinning.

Answer #1

A disk rotates about its central axis starting from rest and
accelerates with constant angular acceleration. At one time it is
rotating at 11.0 rev/s; 35.0 revolutions later, its angular speed
is 21.0 rev/s. Calculate (a) the angular
acceleration (rev/s2), (b) the time
required to complete the 35.0 revolutions, (c) the
time required to reach the 11.0 rev/s angular speed, and
(d) the number of revolutions from rest until the
time the disk reaches the 11.0 rev/s angular speed.

1. A wheel starts from rest and has an angular acceleration of
6.00 rad/s2 . When it has made 3.00 rev its angular
velocity in rad/s is:
2. A circular disk of radius 1.00 m rotates, starting from rest,
with a constant angular acceleration. What is the centripetal
acceleration of a point on the edge of the disk at the instant that
its angular speed is 2.50 rev/s?

Starting from rest, a disk rotates about its central axis with
constant angular acceleration. In 2.00 s, it rotates 44.3 rad.
During that time, what are the magnitudes of (a) the angular
acceleration and (b) the average angular velocity? (c) What is the
instantaneous angular velocity of the disk at the end of the 2.00
s? (d) With the angular acceleration unchanged, through what
additional angle (rad) will the disk turn during the next 2.00
s?

A centrifuge takes 100 s to spin up with constant angular
acceleration (α) from rest to its final angular
speed of 1,875 (rad/s).
What is the angular acceleration (in rad/s2) of the centrifuge
as it spins up?
(Hint: use relationship
between angular velocity and angular acceleration)
(ii) How
many revolutions does the centrifuge make as it goes from rest to
its final
angular
speed? (Hint: use relationship between angular displacement
and
angular
acceleration, and noting that one revolution =
2 rads)...

A Disk Rotates A disk rotates about its central axis starting
from rest and accelerates with constant rotational acceleration. At
one time it is rotating at 11 rev/s. Then 60 revolutions later, its
rotational speed is 16 rev/s.
(a) Calculate the rotational acceleration.
___rev/s2
(b) Calculate the time required to complete the 60 revolutions
mentioned.
___s
(c) Calculate the time required to attain the 11 rev/s rotational
speed.
___s
(d) Calculate the number of revolutions from rest until the time...

A wheel beginning at 25 rpm
rotates with an angular acceleration of 4.2 rad/s2.
After 5.0 seconds, it slows to rest over a time of 20 seconds
a)What is the average angular
velocity of the wheel
b)What is the average speed of a
point on the outside edge of the wheel if the radius of the wheel
is 0.34 m?

A
.13 kg disk is rotating at an angular speed of 57 rad/s. The disk
has a radius of .25m. The disk speeds up for 3 s. After the 3 s
have passed, the edge of the disk is under a centripetal forxe of
313.13 N. What is the centripetal acceleration of the disk at this
time?
What is the final angular velocity of the disk after the 3
s?
What is the angular acceleration during the 3 s interval...

A compact disk, which has a diameter of 12.0 cm, speeds up
uniformly from zero to 4.20 rev/s in 2.90s. (A) What is the
tangential acceleration of a point on the outer rim of the disk at
the moment when its angular speed is 2.00 rev/s ? (B) What is the
tangential acceleration of a point on the outer rim of the disk at
the moment when its angular speed is 3.00 rev/s?

A 44.0-cm diameter disk rotates with a constant angular
acceleration of 3.00 rad/s2. It starts from rest at
t = 0, and a line drawn from the center of the disk to a
point P on the rim of the disk makes an angle of 57.3°
with the positive x-axis at this time.
(a) At t = 2.48 s, find the angular speed of the
wheel.
rad/s
(b) At t = 2.48 s, find the magnitude of the linear
velocity...

PRACTICE IT
A wheel rotates with a constant angular acceleration of 3.25
rad/s2. Assume the angular speed of the wheel is 2.20
rad/s at ti = 0.
(a) Through what angle does the wheel rotate between t
= 0 and t = 2.00 s? Give your answer in radians and
revolutions.
___________ rad
___________ rev
(b) What is the angular speed of the wheel at t = 2.00
s?
___________rad/s
(c) What angular displacement (in revolutions) results while the
angular...

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