Henrik whirls a ball on a string in a horizontal circle above his head, at a steady rate. The ball is accelerating at every instant: its direction of travel never stops changing.
An acceleration has a direction. Which way does this one point?
For Henrik's ball, the center of the circle is his hand. The ball accelerates toward the hand at all times.
An acceleration aimed at the center has a name: it is called centripetal acceleration.
Centripetal means center-seeking.
A rider on a circling swing ride moves at a steady speed. In which direction does her acceleration point?
The direction holds at EVERY instant. As the ball moves around, the center stays put, so the acceleration direction turns with the ball, always aiming inward.
Centripetal acceleration never speeds the ball up and never slows it down. It changes the direction of the velocity, and nothing else.
That is how a steady speed and a nonstop acceleration live together on one circle.
Why the direction is inward, the velocity arrows themselves will show you next lesson.
Henrik's ball is at the 3 o'clock position of its drawn circle, with his hand at the center. Which way does the ball's centripetal acceleration point at that instant?
Find the center: the hand, to the left of the ball at this instant.
Centripetal acceleration points from the object toward the center.
From the 3 o'clock position, the center lies to the left.
It points left, from the ball toward the hand at the center.
A carousel pony is at the 6 o'clock position of the carousel's drawn circle. Which way does its centripetal acceleration point?
Find the center: the center post, directly above the pony on the drawing.
Centripetal acceleration points from the object toward the center.
From the 6 o'clock position, the center lies straight up the page.
It points straight up the drawing, from the pony toward the center post.
The drum spins steadily, and the sock rides its wall. At the 12 o'clock position shown, which way does the sock's centripetal acceleration point?
The car laps the circular track at a steady speed. At the 9 o'clock position shown, which way does its centripetal acceleration point?
Which statement about the centripetal acceleration of an object in uniform circular motion is correct?
What does the word 'centripetal' mean?
An object in uniform circular motion has an acceleration that points toward the center of its circle. Type the two-word name for this acceleration.