Labs & Activities P1C

BIG IDEAS: Measuring Speed and the Acceleration of an Object

Achieving Constant Speed in a high school lab is not as easy or as cheap as you might think. In order for us to achieve decent constant speed we must rely on an electric motor of some sort. Hence, battery powered toy cars or the Pasco Smart cart motor attachment is the way to go. Since the Smart cart motor is very expensive, we will reply on toy cars whenever possible.

Our basic setup usually involves using a motion sensor to keep track of the car's speed. (See diagram above).
A cheaper but a slightly more problematic method that most high school Physics labs deploy is the use of a Ticker Tape timer. (See diagram below).

The problem with the Ticker Tape timer method is that we are not measuring the true speed or acceleration of the object. The object is always being slowed down by the friction force of the ticker tape attached to it.

Lastly, with the advent of the Smartphone, we can actually get pretty accurate and problematic free measurements of an object's speed or acceleration by using a meter stick, the video capture feature on a Smartphone and the formula:

For acceleration, we have a lot of ways to accelerate an object and to measure it in a Physics lab. We can simply give the Smart cart and push and launch it forward with a horizontal acceleration. We can add a fan onto the smart cart and allow it to achieve a uniform acceleration. We can also use a motion sensor and measure the acceleration of a pull back toy car and measure its acceleration. We can of course, also use video analysis to help us find the acceleration of any object that we capture on video.

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