Unit 4 Flashcards
- The apparent outward force on a rotating or revolving body.
- It is an effect of rotation.
- Is fictitious because it is not part of an interaction, and therefore not a true force.
- Is due to the tendency of a moving body to move in a straight-line path.
What moves faster on a disk?
Inside and outside have the same rpm, but the outside part moves faster than the inside.
Can the terms linear speed and rotational speed be used interchangeably?
No. [see sec 10.2]
A satellite is…
constantly changing direction as it travels around the Earth, and so it is constantly accelerating. B/c it is accelerating, it is experiencing a net force, gravity.
straight line around which rotation takes place
Two types of circular motion
Rotation and revolution
motion about an axis located within the body of the object
an axis located within the body of the object
the motion about an axis located outside the body of an object
distance traveled per unit of time
The speed of an object moving in a circular path. Called this because the direction of motion is always tangent to the circle.
aka angular speed. Number of rotations per minute (rpm).
A point farther away from the center travels…
…a longer path in the same time, and therefore, has a greater tangential speed.
tangential speed proportion
tangential speed ~ radial distance * rotational speed or v ~ r*w
What does tangential speed depends on?
Rotational speed and the distance from the axis of rotation
Why does a moving freight train stay on the tracks?
Because their rims are slightly tapered.
An object moving in a circle still undergoes…
…an acceleration, even at a constant speed, because its direction is changing, which is due to net force.
What any object moving in a circle undergoes an acceleration that is directed to the center of the circle.
means “toward the center.”
What would happen if a centripetal force ceased to act on an object moving in a curved path?
the object would move in a straight line.
the centripetal force that holds a car in a curved path while rounding a corner comes from.
comes from the friction between the tires and the road.
When you are riding in a car and it goes around a sharp left-hand corner, why are you pressed against the door of the car?
There is no centripetal force acting to hold you in place.
What causes the centrifugal-force effect?
In a rotating reference frame, what forces act on objects in the rotating system?
Both centripetal and centrifugal forces
Center of mass and center of gravity are…
…closely related, and for many objects, are essentially the same thing
Center of gravity
- The point at the center of an object’s weight distribution, where the force of gravity can be considered to act.
- The lower your center of gravity, the more stable you are.
An object in equilibrium has…
…no net torque acting on it.
When would the center of gravity and the center of mass be in different locations in an object?
Possibly in a very large object when the gravity varies from one part of the object to the other.