Acceleration of a System

Lab Brief

Overall Purpose: To compare the acceleration of a system when calculated theoretically, with the acceleration of a system measured experimentally.

The system must consist of a relatively frictionless mass, m1 being accelerated by a vertically falling mass, m2.

• Students may collaborate to set up,but each student must have their own unique masses and raw data.
• Determine and record all relevant data to determine the acceleration of the system from theory. Include uncertainty in measurements.

What to Hand In

• Full Lab Report
• Acceleration must be predicted by calculation in the hypothesis, assume no friction and massless strings etc.
• Uncertainty must be considered in determined acceleration, (analysis, discussion conclusion etc.)

• It is not simple to determine an uncertainty for time in ticker tape timer experiments. The frequency of the 60Hz power signal is within a few parts per million per day. (It is held tightly for synchronization of power generation equipment on the grid.) If a phase change of the signal happens (because of a large load for example) we would expect automatic systems to correct this within ±1% and in fact this would be rare. For mechanical ticker tape timers the greatest uncertainty is caused by mechanical vibration of the bar and the effects of bar bouncing. A conservative estimate of this uncertainty would be ± one half of 1/60 th of a second or ± 8.3 x10^-3 s. Use this uncertainty for Dt. (Uncertainty for time would be half that value.) For electronic ticker tape timers a very conservative estimate of uncertainty in time would be ±1% of the time between dots. (You could arguably reduce this by a couple orders of magnitude)