Figure 11-28 gives the angular momentum magnitude L of a wheel versustime t. Rank the four-lettered time intervals according to the magnitude
of the torque acting on the wheel, greatest first.
The ranking of time intervals according to the magnitude of torque is
The graph L vs t is given.
The torque acting on the object is equal to the moment of force. The toque is also equal to the product of the moment of inertia and angular acceleration of the object. It can be written as the time rate of change of angular momentum of the object.
Use the concept of torque and from the given graph find angular momentum at given time intervals.
The formula is as follows:
WhereL is angular momentum, is torque andtis time.
From the graph, see that for time intervals A and C the slopes are 0.Therefore, torques are 0 Nm.
For time interval B the slope is positive and for D slope is negative, but here, magnitudes want to be found.So, the slope of time interval D is greater than B.
From this, rank torques from the time intervals,
Therefore, torques can be ranked from the given time intervals using the concept of torque. The rank is,
A man stands on a platform that is rotating (without friction) with an angular speed of his arms are outstretched and he holds a brick in each hand. The rotational inertia of the system consisting of the man, bricks, and platform about the central vertical axis of the platform is localid="1660979279335" If by moving the bricks the man decreases the rotational inertia of the system to 2.0 kg.m2.
(a) What are the resulting angular speed of the platform?
(b) What is the ratio of the new kinetic energy of the system to the original kinetic energy?
(c) What source provided the added kinetic energy?
The rotor of an electric motor has rotational inertia about its central axis. The motor is used to change the orientation of the space probe in which it is mounted. The motor axis is mounted along the central axis of the probe; the probe has rotational inertia role="math" localid="1660985808865" about this axis. Calculate the number of revolutions of the rotor required to turn the probe through about its central axis.
Question: A sanding disk with rotational inertia is attached to an electric drill whose motor delivers a torque of magnitude 16 Nm about the central axis of the disk. About that axis and with the torque applied for 33 ms,
(a) What is the magnitude of the angular momentum? (b) What is the magnitude of the angular velocity of the disk?
Question: A uniform solid sphere rolls down an incline. (a) What must be the incline angle if the linear acceleration of the centre of the sphere is to have a magnitude of 0.10 g? (b) If a frictionless block were to slide down the incline at that angle, would its acceleration magnitude be more than, less than, or equal to 0.10 g ? Why?
94% of StudySmarter users get better grades.Sign up for free