Physics Home > Teaching Labs > Mechanics > The Inclined Air Track

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Prerequisites

Lab Activities

Measurement of the acceleration of gravity. An air track is inclined and a car is allowed to slide down and collide with a bumper at the bottom of the track. After the collision, the car travels back up the track but to a height less than the original height. If the car is left alone, this process repeats itself until all the energy is lost. Three assumptions are made about the system: (1) the only forces acting on the car during its travel up and down the track is gravity, (2) all of the energy losses occur in the collision between the car and the bumper, and (3) the same relative amount of energy is lost during each collision. Starting with these assumptions and using the laws of motion for a uniformly accelerating object, an expression for g is derived. The students measure an experimen-tal value for g using this expression and compare it to the accepted value. Experimental values for g generally are within 5-10% of the accepted value (usually on the low side).

Course Level

Introductory: P3, P13, P15

Student Handouts

Equipment

Number of set-ups available: 20 Per lab station: 1 airtrack/cover 1 air cart 1 stopwatch 1 meterstick 3 brass spacers (1 thick; 2 thin) Per class: - air supplies (1 per three tracks) 1 demonstration vernier caliper 1 demonstration semi-log graph chalkboard

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