Conical Pendulum

Conical Pendulum &
Centripetal Force

Equilibrium in rotational motion is a tricky concept. This experiment helps you explore precisely that. It also helps you learn why is the earth bulged at the equator and squished at the poles. Rotating a stone attached to the end of a string ultimately lifts it. See this in action, and that too quantitatively.

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The Experiment

Using video for observing a physical phenomenon.
Calculating uncertainties from the measurements taken from a video.
Observing the effect of angular velocity on geometric parameters of conical motion.
Investigating discrepancies between theoretical predictions and experimental observations.
Study dynamic equilibrium, angular velocity, centripetal forces, and acceleration due to gravity.

How does it work?

This experiment uses a Conical Pendulum to familiarize the experimenter with dynamic equilibrium in rotational motion. In this investigation, we identify the free body diagram of a horizontally whirling object and see how the object lifts as its speed goes up. The lift apparently defies the downward pull of gravity but we see how a angular balance of forces allows the object to swirl at a certain lift angle. As the speed of the object changes, the forces adapt and preserve the delicate balance.

In this experiment, the angular speed of a pair of spheres moving in a horizontal plane is controlled by a stepper motor. It is also monitored in real-time and displayed on a computer screen. We then record this motion using a video camera and use an image processing software to find the geometric parameters of the system. This information is used to make quantitative assessments. This experiment is a fine example of how video analysis can help understand the confusing nature of the rotational motion.

Overview