A test driver holds her car at exactly 15 m/s around a circular test loop. The speedometer needle does not move, and the steering wheel does not move either. Lap after lap, nothing about the motion changes.
Motion this steady gets its own name. What counts, and what does not?
Run the car through four moments. On the loop at a steady 15 m/s: a circle, at a constant speed.
The same car leaves the loop onto a straight road, still at 15 m/s. The speed is constant, but the path is no longer a circle.
The same car rejoins the loop and settles at a steady 15 m/s again. A circle, at a constant speed, as before.
The same car stays on the loop but accelerates out of a slow corner, its speedometer climbing. The path is a circle, but the speed is no longer constant.
Two ingredients matter: the path is a circle, and the speed is constant. Both held in moments one and three. Each failed once, in moments two and four.
The steadily turning tip of a clock hand is uniform circular motion. So is a Ferris wheel cabin at the ride's steady cruising rate.
Uniform means the speed is unchanging. Circular means the path is a circle. Both words carry weight, and both must hold.
A carousel horse circles at a steady rate, never speeding up or slowing down. Is the horse in uniform circular motion?
A motorcycle rounds a circular track while braking for a pit stop, slowing the whole way. Is the motorcycle in uniform circular motion?
The tip of a clock's second hand sweeps around steadily. Is this uniform circular motion?
Is the path a circle? Yes: the tip stays one hand-length from the center.
Is the speed constant? Yes: the hand sweeps steadily.
Both ingredients hold.
Yes. The tip is in uniform circular motion.
A Ferris wheel is starting up: the cabins ride the wheel's circle while the wheel turns faster and faster. Is a cabin in uniform circular motion?
Is the path a circle? Yes: the cabin stays on the wheel's rim.
Is the speed constant? No: the wheel is turning faster and faster.
One ingredient fails.
No. The cabin is not in uniform circular motion while the wheel speeds up.
Which of these movers is in uniform circular motion?
A toy train runs a circular track at a constant speed, and that makes it uniform circular motion. Which statement gives the reason?
Four friends describe their rides home. Which ride is uniform circular motion?
A marble rolls around a circular groove at a constant speed. Type the three-word name for this kind of motion.