Lab Instructions
AP Physics C Mechanics – Constant Acceleration Lab
Page 1/8
Purpose and Approach: The purpose of this lab is to understand quasi 1-dimensional motion
under conditions of constant acceleration and to compare predicted motion with actual
observations. This is a qualitative lab. You will be describing the observed shapes of the curves
and determining whether your predicted shapes are observed. Your lab report will be about
describing how you achieved each of the different graphs.
Note: If the set of curves states “one track” then the acceleration is constant
throughout the graph. If the set of curves states “two tracks” then there are two
different sections, each of constant acceleration.
Step 1: Preparing the target curves.
For each case you are provided with three graphs (x vs. t, v vs. t, a vs. t). One of these curves
is filled in. You must use the data provided to fill in the other two curves. Show these curves
to your teacher before you move to the second section.
Step 2. Generating the data.
Set up one or two tracks and the motion detector and endeavor to start the cart with the proper
initial conditions for position and velocity to generate curves which agree with the three target
curves. You will demonstrate success by recording position, velocity, and acceleration vs.
time curves using motion detectors with the labquest tool and then storing your results on
memory sticks. When you get good qualitative agreement between the target curves and the
actual curves save the data onto a memory stick. The data will be emailed back to you so that
you can include the data in a lab report.
In order to work with somewhat more interesting graphs, each group will work with two plastic
tracks for the last three curves. They must be set next to each other to allow for an almost
smooth transition with the help of some blocks and by fine adjusting the feet on the tracks. We
will consider this to be piecewise continuous for variables of position and velocity and abruptly
changing for acceleration.
Experimental Concepts –
1. Adjusting the value of the acceleration:
We use the fact that with a cart rolling on a ramp you can
control the acceleration by adjusting the tilt. If  is the
angle that the board makes with the horizontal then
a  g sin  . (We will prove this later in the year.)
Question 1.1 Convince yourselves that this formula
makes sense at   0 and at    / 2 .

a

2. Orientation: You will have to arrange the motion detector so that the curve that you observe
directly matches the target curve that you are provided.
3. Making motion measurements with angular differences: The motion detectors are designed
to work with tracks but may not work well with tracks that have bends in them. For this reason
you may have to adjust the feet at the end of one of the tracks to make the transition as smooth
as possible.
Lab Instructions
AP Physics C Mechanics – Constant Acceleration Lab
Page 2/8
4. Initial conditions: You may start the motion either at rest or by giving the cart a push in
either direction.
Materials:
1 rolling cart, 2 plastic tracks, 1 motion detector, 1 memory stick, 1 labquest computer.
Typical diagram showing (a) arrangement
of tracks, (b) initial location and direction

of velocity ( v0 ) of cart and (c) location of
motion detector. You will make one
diagram like this for each case that you
analyze.

v0
Motion
detector
Lab Report
There are six cases that you will document. Each case should be its own section and include a)
the three target curves, b) the three measured curves, c) a diagram like the one above showing
the ramps and initial conditions used to generate the data.
AP Physics C Mechanics – Constant Acceleration Lab
Lab Instructions
Case 1. (One track)
0
position x/L
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2e
tim
2.5
3
3.5
4
0
0.5
1
1.5
2
tim e
2.5
3
3.5
4
0.5
1
1.5
2
2.5
3
3.5
4
velocity (rel scale)
2.5
2
1.5
1
0.5
0
acceleration (rel scale)
5
3
1
-1 0
-3
-5
tim e
Page 3/8
AP Physics C Mechanics – Constant Acceleration Lab
Lab Instructions
Case 2. (One track. The dot shows the initial position)
0
1
position x/L
0.8
0.6
0.4
0.2
0
-0.2
0
0.5
1
1.5
2
tim e
2.5
3
3.5
4
0
0.5
1
1.5
2
2.5
3
3.5
4
2.5
3
3.5
4
1.5
velocity (rel scale)
1
0.5
0
-0.5
-1
-1.5
tim e
acceleration (rel scale)
5
3
1
-1 0
0.5
1
1.5
2
-3
-5
tim e
Page 4/8
AP Physics C Mechanics – Constant Acceleration Lab
Lab Instructions
Case 3 (One track)
0
position x/L
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
tim2e
2.5
3
3.5
4
-0.2 0
0.5
1
1.5
2
2.5
3
3.5
4
2.5
3
3.5
4
0.2
velocity (rel scale)
0
-0.4
-0.6
-0.8
-1
-1.2
tim e
acceleration (rel scale)
5
3
1
-1 0
0.5
1
1.5
2
-3
-5
tim e
Page 5/8
AP Physics C Mechanics – Constant Acceleration Lab
Lab Instructions
Case 4. (Two tracks.)
0
position x/L
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
tim2e
2.5
3
3.5
4
0
0.5
1
1.5
2
tim e
2.5
3
3.5
4
2.5
3
3.5
4
velocity (rel scale)
1.2
1
0.8
0.6
0.4
0.2
0
acceleration (rel scale)
1
0.5
0
0
0.5
1
1.5
2
-0.5
-1
tim e
Page 6/8
AP Physics C Mechanics – Constant Acceleration Lab
Lab Instructions
Case 5. (Two tracks)
0
1.2
position x/L
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
tim2e
2.5
3
3.5
4
0
0.5
1
1.5
2
2.5
3
3.5
4
2.5
3
3.5
4
1.5
velocity (rel scale)
1
0.5
0
-0.5
-1
-1.5
tim e
acceleration (rel scale)
1
0.5
0
0
0.5
1
1.5
2
-0.5
-1
tim e
Page 7/8
AP Physics C Mechanics – Constant Acceleration Lab
Lab Instructions
Case 6 (Two tracks. The dot shows the initial location.)
position x/L
0
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2 0
-0.3
0.5
1
1.5
2
2.5
3
3.5
4
2.5
3
3.5
4
2.5
3
3.5
4
tim e
2.5
velocity (rel scale)
2
1.5
1
0.5
0
-0.5 0
0.5
1
1.5
2
-1
-1.5
tim e
acceleration (rel scale)
1
0.5
0
0
0.5
1
1.5
2
-0.5
-1
tim e
Page 8/8