Rotational Motion Flashcards
The greater the rotational inertia, the more difficult to change the?
rotational speed of an object.
What law states that the energy cannot be created or destroyed, but it can be transferred.
the first law of thermodynamics or also known as LAW OF CONSERVATION OF ENERGY
The resistance of an object to changes in its
rotational motion is called
rotational inertia
(sometimes moment of inertia).
This is is required to change the rotational
state of motion of an object.
TORQUE
What happens In the object with the absence of a net torque
a rotating object keeps rotating, while a non-rotating object stays non-rotating.
The greater the distance between an object’s mass concentration and the axis of
rotation is equal to
The greater the rotational inertia.
rotational inertia of an object is not necessarily a fixed quantity It is greater when the mass within the object is?
Extended from the axis of rotation.
When swinging your leg from your hip, why is the rotational inertia of the leg less when it is bent?
The rotational inertia of any object is less when its mass is concentrated closer to the axis of rotation.
The major axes of rotation of the human body are the ___ axis, the ___ axis, and the ___ axis.
longitudinal (head to toe), transverse, medial (front to back)
How does rotational inertia affect how easily the rotational speed of an object changes?
The greater an object’s rotational inertia, the more difficult it is to change the rotational speed of the object
The three major axes of rotation of the human body are
at right angles to one another and pass through the center of gravity
The human body’s longitudinal axis has the
least rotational inertia of the three body axes.
You rotate about your _____ when you perform a somersault or a flip.
transverse axis (2)
Objects of the same shape but different sizes accelerate equally or not equally when rolled down an incline.
equally
Which will roll down an incline with greater acceleration, a hollow cylinder or a solid cylinder of the same mass and
radius?
The hollow cylinder—has the greater
rotational inertia.
The solid cylinder will roll with greater acceleration.
Second possible answer: the cylinder with the SMALLER ROTATIONAL inertia because the cylinder with the GREATER ROTATIONAL inertia requires more time to get rolling.
A heavy iron cylinder and a light wooden cylinder, similar in shape, roll down an incline. Which will have more acceleration?
The cylinders have different masses, but the same rotational inertia per mass, so both will accelerate equally down the incline.
NOTE: All objects of the same shape have the same “laziness per mass” ratio. (THIS EXCLUDES A HOLLOW AND SOLID OBJECTS)
Would you expect the rotational inertia of a hollow sphere about its center to be greater or less than the rotational inertia of a solid sphere?
Yes greater, the rotational inertia of a hollow
sphere would be greater than that of a same-mass solid sphere for the same reason: the mass of the hollow sphere is farther from the center.
What happens when objects of the same
shape but different sizes are rolled down
an incline?
Objects of the same shape but different sizes accelerate equally when rolled down an incline.
Newton’s first law of inertia for rotating systems states that an object or system of objects will maintain its angular momentum unless
acted upon by an unbalanced external torque.
defined as the product of rotational inertia
Angular momentum (Anything that rotates keeps on rotating until something stops it)
An external net force is required to change the
Linear momentum and angular momentum of an object
How does Newton’s first law apply to
rotating systems?
An object rotating about an internal axis tends to keep rotating about that axis.
Rotating objects tend to keep rotating, while
non-rotating objects tend to remain non-rotating.
The resistance of an object to changes in its
rotational motion is called rotational inertia
(sometimes moment of inertia).
Angular momentum is conserved when
no external torque acts on an object.
law of conservation of angular momentum states that if no unbalanced external torque acts on a rotating system
the angular momentum of that system is constant.
