Eugenia skates in a circle: Observational Experiment

Aim

To find a pattern in the direction of the vector sum of the forces exerted by other objects on an object moving in a circle at constant speed.

Prior Knowledge

• Newton's Laws. Free-body diagrams.

Description of the Experiment

Eugenia tries to skate in a circle. At first she fails when she tries to turn by tilting her body. Then she demonstrates two ways in which it is possible to skate in a circle. Draw a force (free-body) diagram for Eugenia at several points of the circle for each experiment.

Youtube movies can be stepped frame by frame using the , and . keys on your keyboard. If you want to download the movie to your computer, right-click or control-click HERE.

Questions

• When Eugenia tries to skate in a circle the first time, why does it not work? Draw a free-body diagram of forces exerted on Eugenia by other objects.



• When Eugenia skates in a circle with a rope, what is the role of the rope? Be specific. Draw a free-body diagram of forces exerted on Eugenia by other objects.



• When Eugenia skates in a circle without a rope, how does she ensure that she remains in circular motion? With what object does Eugenia interact? In what direction is this object pushing her? Draw a free-body diagram of forces exerted on Eugenia by other objects.



• When Eugenia moves in a circle, is her velocity changing? Assume that the speed of Eugenia remains almost constant and find the direction of her acceleration assuming that the direction of her acceleration is the same as the direction of the velocity change vector.