Uses the frictionless air track (with the PASCO air pump) and 2 strategically placed PASCO photogates. A weight is suspended on one end over a pulley and attached to a mass on the track. The time it takes for the mass to travel between the photogates is measured using the datastudio file "M to 2M.ds" on the demonstration laptop. If the photogates are properly placed, this time will be exactly 3 seconds. Then the same hanging mass is then used to accelerate a cart that has exactly twice the mass of the original. It can be shown that this time should be a factor square root of 2 longer than the previous time (in the limit m << M, where m is the hanging mass, and M is the original cart mass), around 4.24 seconds.

**Equipment Location:** South side of demo room, on table

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