Newton's Second Law: Atwood Machine

PHY 100

Demonstrates how force is related to the acceleration of the mass to which it is applied. The Atwood Machine allows the net force on a mass to be varied in order to see the effect on velocity and acceleration of that mass. Students will first calculate the theoretical acceleration of a system using merely given weights and Newton's 2nd Law. They then verify that result by setting the masses into motion and measuring distance and time to allow an alternative calculation of acceleration using kinematic formulas.

Equipment

Notes

Masses must be hung properly and ready for use. Travel distance of system must be one meter or more with pulley mounted near chest height. Pulley wheel must be exactly vertical and oriented to the right of mount so that load will not unscrew mount from rod. Bolt through wheel bearing should only be finger tight at most. Do not use pulleys marked as defective with X. Contact instructor for choice of mass hanger and/or trailing strings. The trailings strings are in a small plastic bag in D69. Each lab bench should already have a table clamp, rod, and lattice rod clamp attached to the rod.

Make sure that the room has plenty of paper.

If the lab setup list only says Newton s Second Law, check with supervisor whether this should be the old Atwood setup, the computer-based Atwood setup, or the carts and track setup.

Along with the initial apparatus set-up, supply a sufficient number of the appropriate paper procedure handouts for all of the lab sections that will use the set-up over the course of the week. Print the PDF, duplicate to double-sided pages, staple, and leave pile on instructor's table prior to first use of set-up.