Apologia Physics: Motion

The kids are working on several motion labs: Ramps and Balls, Go Pro with Hot Wheels Car, and Are You Speeding?  The introduction to Motion allows for experimentation.  Are You Speeding? uses Pasco Spark with the motion sensor.  The kids literally follow the Sparkvue lesson to learn how to collect motion data with a motion sensor.
On Tuesday, the kids did experiments with ramps and balls.  (The ramps are 4x6 boards cut into one meter lengths at Lowes.  The ball is a Pinkie ball.)  The object was to demonstrate average speed and acceleration.  They leaned one board against a book shelf.  The other board was placed on the floor at the base of the first board.  How could they measure the acceleration of the ball as it rolled down the ramp?  We do not have a radar gun to measure the instantaneous speed at the bottom of the ramp.  We approximated the top speed of the ball by measuring the time it took to cross the one meter board on the floor; the assumption being that the ball would not slow down significantly on the flat portion.  After we measured the elapsed time of the ball on the one meter board on the floor, we compared that to the starting speed, which in this case was zero, got the difference and divided by the time elapsed by the ball rolling down the ramp.   This was the acceleration experienced by the ball on the ramp.  It is crucial that the students calculate the acceleration by dividing the change in speed by the time and include all units of measure.  Acceleration is changed in speed divided by time.  Therefore if they set up the calculation correctly the resulting measure is meters per second squared.



The kids used Hot Wheels track with the Go Pro Hero and the Hot Wheels car to measure the same as above.  By observing the GoPro video, we could determine the speed by counting the frames of video recorded by the car covering the measured meter.  It helps to put some colored tape on the beginning and end of the measured meter of Hot Wheels track so one can see the beginning and end of the measured distance.  After counting the frames, one must look up the frames per second for the GoPro and convert frames to seconds.  We were not able to use the motion sensor to determine instantaneous speed but they had fun trying it.

We used the motions sensor to measure a student's walking back and forth.  This measures the displacement from the beginning point.

The assignment for Tuesday is to read all or module 2 and complete the on-your-own problems.