• Open the
Logger Pro
file for Part III, and then try to move the cart in such a manner
as to
match one of the following four prescriptions for at least a two-second
time duration, repeating as necessary in order to accomplish the
prescription. You can Autoscale them with the “A” button in the
top ribbon of the Logger Pro window. If you have time, each
student partner should do all four of the following
prescriptions. If you have fewer than fifteen minutes left, you
should each take a pair of prescriptions.
1. x increasing, vx
reasonably constant
2. x decreasing, ax positive
3. vx positive, ax positive
4. vx negative, ax negative
• When you have good data for each of the four
prescriptions, copy and paste an example into the box below Question 2
of your worksheet, following the instructions for Question 2.
• In this part, only x(t) and v
x(t) are
plotted
(a
x(t) is not). The reason for this is that v
x(t)
and a
x(t)
values are GENERATED from the x(t) data (which are actually MEASURED –
by the motion detector), v
x(t) through one process called
numerical
differentiation, and a
x(t) through two such processes, with
the result
that a lot of noise shows up in the a
x(t) data. In
subsequent
experiments you will be shown a sophisticated, computer-appropriate way
to extract excellent average acceleration values from the Logger Pro
data at hand.
• Yet you only need the x(t) and v
x(t)
graphs in
order to figure out how to match these various prescriptions, even if
acceleration is prescribed! How indeed? In fact, all you
really need is the x(t) graph OR the v
x(t) graph! If
you don’t
understand this point, be sure to ask your lab instructor about it if
you and your partner cannot figure out the answer by yourselves.