Unit C - Circular Motion, Work, and Energy Flashcards
What force acts on passengers in a circular carnival ride
An inward force acts on the passengers to keep them moving along a circular path. The seat pushes on the passengers, forcing them to remain on a circular path
Centripetal
An inward force / center-seeking force based on its direction
Horizontal Plane
A plane perpendicular to the radius of the Earth, usually used to suggest that there is no vertical component to motion or force
Uniform circular motion
The motion of an object with a constant speed along circular path
Explain why the ball moves the way it does once the strong has been cut
When the ball was released, it travelled in the direction in which it was moving the moment the strong was cut. This occurs because the string is no longer pulling on the ball and Newton’s first law comes into play
Newton’s First Law
A body continues in its state of rest or motion in a straight line with a constant speed unless an external, unbalanced force acts on it
Newton’s Second Law
The rate of change of velocity of an object is proportional to and in the same direction as the unbalanced force acting upon it; F = ma
Axis of Rotation
Imaginary line that passes through the center of rotation perpendicular to the circular motion
If you ride through puddles after a rainfall, you’ll come home with water splashed on your back. Why?
As the wheel passes through the puddle, some of the water adheres to it. As the wheel rotates upward out of the puddle, excess water flies off. When it flies off, it moves along a path that is tangential to the wheel. Speed of water is determined by speed of the wheel.
How is inward force related to speed
Fc = v^2; Inward force = speed squared
Cycle
One complete back-and-forth motion or oscillation
Rotation
One complete cycle for an object moving in a circular path
Period
The time required for an object to make one complete oscillation (cycle)
Rotational velocity can be measured indirectly by
Measuring the time (period (T)) it takes for one complete rotation (cycle or revolution), measured in s/cycle
Frequency
The number of cycles per second, measured in hertz (Hz)
Relationship between period and frequency
Inverse of each other; T = 1/f, f = 1/T
Distance around a circle
Circumference (c =2πR), divided by the time it takes for one revolution (period = 5). Thus, the speed of anything with circular motion is v = 2πr/ T (r has to be in meters, T has to be in seconds)
Centripetal acceleration depends on
Only the speed and radius of the circular motion, mass does not affect it. However, the larger the mass, it was experience a larger centripetal force
If you triple the speed which you twirled a ball on a string, how would it affect the size of the inward force (tension) on in the string
Fc = mv^2/r. Centripetal force is calculated by mass * velocity^2 / radius. If we triple velocity 3^2 is 9, so we would increase the tension in the string by 9 times.
Weightless
Experience little apparent gravitational pull
Tension
A stress that tends to strech an objecet
Vertical circular motion
Motion in a circular path where one diameter of the circle is vertical
At the top and bottom of a vertical circle, the inward force is the sum of the
Tension and gravitational force vectors. F inwards = Ft + Fg
At which point in the vertical circle do the tension and force due to gravity act in the same direction to produce the inward force
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