chapter 7 Flashcards
rotational motion
motion of obejcts that spin about an axis
what is the angular position
the angle tells us how far we have moved
what is the arc length
it tells us the distance the particle traveled along a circular path
when angular position, when is the movement positive? when is it negative?
when theta is measured counterclockwise from the positive x-axis, it is positive
when theta is measured clockwise from the positive x-axis, it is negative
what is angular position
the position of the particle measured ΞΈ from positive x-axis
what is the angular speed
the absolute value of the angular velocity
Angular velocity
the angular displacement though which the particle moves each second, denotated by w
whatis the difference between v (speed) and w (angular speed)
the speed (v) refers to the different speeds at which different points on the rotating body may be rotating whereas angular speed is the referring to the angular displacements moved per unit of time
(for example, points that are further away from the center have to move at a faster speed in order to complete the same amount of revolutions in the same amount of time as a point that is closer)
whats the formula relationship of v and w
v=wr
what is a rigid body
it is a rotating object that has no objects on it that move independently, the shape remains the same
on a rigid body, what do two points at different distances from the center share or differ?
they have the same angular velocity but different speeds at which they complete the revolution
for points further away from the axis of rotation, what is true about their speed and angular velocities relative to a point closer to the center?
points furhter away will have a faster speed (v) even though they might have the same angular velocity (w)
what is angular acceleration
π= βw/t, is the change in angular velocity over time
wben π and w have the same signs, what is true of the motion
it is speeding up
when π and w have different signs, what is true of the motion
it is slowing down
whats the difference between centripetal acceleration and tangential
centripetal acceleration keeps the object in a circular path but doesnβt change the speed, tangential acceleration speeds up the velocity
what happens to the centripetal acceleration as the overall speed increases
the centripetal acceleration increases
how do we find the tangential acceleration in relation to angular acceleration
at= angular acceleration x radius
what does torque cause
angular acceleration
what does the ability of a force to cause a rotation depend on?
it depends on the magnitude of the force, the distance (r) from the pivot and the point of force application, and the angle at which the force is applied
what is the radial line?
it is the distance fom the axis of rotation to the point of application of the force
what component of the force effects the torque?
the perpendicular component
if you have a greater distance (r) from the axis, what happens to the torque
a greater distance causes a greater torque
what is the line of action
it is the line through where the force goes through
what is the moment arm
it is the perpendiuclar distance from the line of action to the pivot
if an objects center of gravity is directly below the pivot point, what happens to the motion
it is at rest, the perpendicular force is zero
what is the moment of inertia
it is the rotational equivalent of mass
when do we have a larger inertia?
when the mass is further from the axis of the rotation
what direction of force will cause a greater torque
one that is perpendicular to the radial line
