Chapter 17 - Motion in a circle Flashcards
An object rotating at a steady rate is said to be in what?
Uniform circular motion
What is the equation for velocity on the perimeter of a circle?
v = 2πr/T
r = radius
T - time period
What is the angular displacement?
2∏t/T = 2∏ft
- angle would be in radians
What is the equation for angular speed? (omega)
- angular displacement per second.
angular speed = angular displacement/t = 2∏/T = 2∏f
What is the unit of angular speed?
Radians per second (rad/s)
Why is the object accelerating when in circular motion when the speed is constant?
Velocity is constantly changing as it’s changing direction, so it’s accelerating.
Draw an object in circular motion around a centre point. Draw acceleration and velocity.
Acceleration towards centre of circle and velocity perpendicular to this, at tangent to the circle.
What is centripetal acceleration? Give the equation
Acceleration of an object in circular motion, due to change in direction of the velocity towards centre of circle.
a = v^2/r = angular speed^2 x r
What does centripetal mean?
towards centre of circle
What is the centripetal force?
Resultant force on an object moving around a circle at constant speed. Acts towards centre of circle. (same as centripetal acceleration)
What is the equation for centripetal force?
F = mv^2/r
(Newton’s second law applied to: a = v^2/r)
Why must there be a centripetal force?
If the object is accelerating, then there must be a resultant force. (Newton’s first law)
