# Centripetal Acceleration Experiment

• The students will use the data they collect and analyze to write an equation that expresses the mathematical relationship between the net force, the mass, the linear velocity and the radius of the mass carriage with respect to the axis of rotation, in order to understand forces acting on objects traveling in a circle. There is a force sensor that is registering the net force acting on the mass carriages and a photogate that is measuring the angular speed of the spinning arm.

Here’s the link on the Vernier Software & Technology webpage for the experiment the students were working on this morning:  https://www.vernier.com/experiments/phys-am/12a/centripetal_acceleration/  (The actual experiment procedure document can’t be posted to a website without violating their copyright.)

The AP Physics 1 learning objectives we are working on with this experiment are the following in the context of Circular Motion:

4.A.2.3: The student is able to create mathematical models and analyze graphical relationships for acceleration, velocity, and position of the center of mass of a system and use them to calculate properties of the motion of the center of mass of a system. [SP 1.4, 2.2]

4.A.3.1: The student is able to apply Newton’s second law to systems to calculate the change in the center-of-mass velocity when an external force is exerted on the system. [SP 2.2]

 3.A.2.1: The student is able to represent forces in diagrams or mathematically using appropriately labeled vectors with magnitude, direction, and units during the analysis of a situation. [SP 1.1] 3.A.3.1: The student is able to analyze a scenario and make claims (develop arguments, justify assertions) about the forces exerted on an object by other objects for different types of forces or components of forces. [SP 6.4, 7.2]

3.B.1.2: The student is able to design a plan to collect and analyze data for motion (static, constant, or accelerating) from force measurements and carry out an analysis to determine the relationship between the net force and the vector sum of the individual forces. [SP 4.2, 5.1]

# Acceleration of a Falling Object

• From Chasteen:

I wanted to take a second to brag on my on-level physics students, because they are doing a great job. They learned how to use video analysis and LoggerPro Graphical Analysis software to determine the acceleration of a falling object. They dropped a tennis ball, analyzed it’s acceleration, then had to design a parachute to reduce the acceleration of the tennis ball. They had to provide evidence of how much the parachute had reduced the acceleration by evaluating the “A” parameter of their quadratic fits. The “A” parameter is half of the ball’s acceleration. All of the student teams were successful in reducing the ball’s acceleration!

Below are one team’s pair of graphs and a picture of the parachute they designed.

Drag Force Lab

• Use video analysis to measure the acceleration of a tennis ball in free fall.
• Make a parachute to reduce the acceleration of the tennis ball.
• Use video analysis to measure the new acceleration of the tennis ball.
• If you can make the tennis ball have a terminal velocity you get extra points!
• Place copies of your analyzed graphs below.   