Author Archives: Cary Busby

Students introduce water vapor and smoke into a bottle, pressurize it, and quickly release the pressure. The rapid depressurization decreases the temperature of the water vapor, which encourages it to condense around the smoke particles. A cloud forms.

The first experiment will use very basic equipment to measure an important quantity, the acceleration of an object in freefall. This is also known as the acceleration due to gravity, or g. The acceleration due to gravity is nearly the same at all points on the earth’s surface, 9.8 m/s2. You will compare your result to this accepted value. The second experiment will use a data-logger and photogates to measure the acceleration due to gravity. The “picket fence” has been used since photogates were developed to measure acceleration. The “pickets” block the photogate in sequence, giving a series of velocity readings. Using the velocities and the times between those velocities, the data-logger (or the student) can calculate the acceleration of the picket fence. The third experiment will use a data-logger and motion sensor (or sonic ranger) to measure the acceleration due to gravity.

This experiment will use photogates to find the speed and acceleration of a car rolling down a ramp. Photogates use a single beam of ultraviolet light which goes from one arm of the gate into a receiver in the other arm. A data logger connected to the photogate will record the time that the beam is blocked by an object passing through the gate. Photogates allow us to accurately measure times that would be too short to measure with a stopwatch.

Measuring Constant Velocity- A moving object experiences a change in its position in a certain time. For constant velocity, the change in position over each equivalent time period is constant. Students will graph the position vs. time of a moving car. The graph will be a straight line whose slope is the car’s velocity.