3. Connect the remaining plug of the Timer Switch to Digital
Input 1 of the interface.
4. Connect the Time-of-Flight Accessory to Digital Input 2 of
the interface.
NOTE: If you are using a PASPORT interface
with a Digital Adapter (PS-2159), connect the
Digital Adapter to a PASPORT port of the
interface, then plug the Timer Switch and Time-
of-Flight Accessory into Digital Inputs 1 and 2 of
the adapter.
5. On the visual representation of the interface in Hardware
Setup, click the yellow circle over Digital Channel 1 and
select Photogate from the list. Then click the yellow circle
over Digital Channel 2 and select Time Of Flight
Accessory.
Figure 7. Configuring the digital channels of a 550 Universal Interface
(UI-5001) for this experiment in PASCO Capstone.
6. Select Timer Setup from the Tools palette, then select
Pre-Configured Timer and click Next. (See Figure 8 for
this and the following few steps.)
7. Make sure that both Photogate, Ch 1 and Time Of Flight
Accessory, Ch 2 are checked, then click Next.
8. Select Time Of Flight (1 gate) and click Next.
9. Make sure that Time Of Flight is selected from the list of
measurements to make visible, then click Next.
10. Enter a custom name for the timer if desired, then click
Finish.
11. Create a Digits display by double-clicking the Digits icon in
the Displays palette.
12. Click <Select measurement> and select Time of Flight to
assign the display to measure the fall time.
Data collection
1. In Capstone, click Record
. This will start the experiment
clock, indicating that the program is ready to collect data.
2. Press the Timer Switch button to release the object from
the Drop Box. When the object hits the Time-of-Flight pad,
the display in Capstone will record the fall time.
To time another object, hang the object from the Drop Box, wait
until the LED on the Drop Box stops blinking, and repeat the
previous two steps.
Figure 8. The proper timer configuration for performing experiments with
the Discover Free Fall System in Capstone.
Suggested experiments
Fall time of different objects
Keeping the drop height constant, measure the free fall time of
different objects. Measure the drop height from the Time-Of-
Flight pad to the bottom of the object when it is hanging from the
Drop Box. You will need to adjust the Drop Box position slightly
for differently sized objects to ensure this height stays constant.
Time each object several times to make sure you get an
accurate measurement.
Compare objects of various sizes, masses, and densities. How
does each factor seem to affect fall time?
If the only force acting on the objects is gravitational force, you
would expect the fall time to be the same for every object. Do
you find this to be the case?
Fall time versus height
Time a stainless steel ball dropping from several different
heights. Use as wide a range of heights as possible.
Plot fall time (t) versus height (h) on a graph. Is the relationship
linear?
Plot t
2
versus h. Is this relationship linear?
For an object falling with constant acceleration a, the relationship
between t and h is given by:
Use your data to find a in this case.
Repeat the procedure with the large hollow ball. Does it
accelerate at a constant rate? How can you tell?
Discover Free Fall System | ME-9889
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