15
If you want to improve force readings, there are two steps you can take. The quickest
and easiest step is
zeroing
the force sensor. This means defining a certain orientation
and condition as zero force and subtracting that amount from all future readings. In
most cases zeroing is all you need to do before force sensor experiments. It adjusts
for any minor offset in the force readings. It also adjusts for the orientation of the
WDSS. The sensor is sensitive enough to measure the weight of its hook or bumper.
This means that the force reading will change, depending on the orientation of the
WDSS. To minimize this effect, simply place the sensor in the orientation in which it
will be used (horizontal or vertical) and choose Zero from the Experiment menu or
use the Zero icon on the toolbar. This will define the current reading as 0 N of force.
If you want to improve the calibration, it is easy to recalibrate. Simply follow the
same procedure that is used in calibrating most Vernier sensors–a two point
calibration. The first point should be with no force applied.
1. Orient the WDSS with the hook connected to the force sensor pointed downward.
2. Select Calibrate from the Experiment menu and then select the force sensor.
3. Remove all force from the sensor.
4. Enter
0
as the first known force.
5. Now hang a 1 kilogram mass from the hook on the force sensor.
6. Enter the weight of this mass (9.8 newtons) as the second known force.
We recommend calibrating with a 1 kg mass because of the way the force sensor
works. As mentioned above, the WDSS force sensor really is two force measurement
systems in one package. One measures forces in the range of
±
10 N range, and the
other measures force in the
±
50 N range. The 1 kg (9.8 newton) mass is a good
compromise for calibrating both of these force sensors together.
Note that since the calibration process happens in the vertical orientation, if you are
going to then take force readings in a horizontal (or other non-vertical) orientation,
you should zero the force sensor after calibration, with it held in the proper
orientation.
16
Mounting on a Dynamics Cart
The WDSS was designed for easy mounting on a Vernier or Pasco dynamics cart for
force and acceleration experiments.
Mounting on a Vernier Dynamics Cart
For connection to a Vernier Dynamics cart use a 5/8" × 10-24 binding barrel and a
hex-head bolt (1" × 10-24). First place the bolt head in the middle slot of the top of
the Vernier dynamics cart. Then lower the WDSS on top of the cart and insert the
binding barrel in the large hole of the WDSS. The bolt threads into the binding
barrel. Tighten the binding barrel. The process is shown in the series of photos
below:
Mounting on a Pasco Dynamics Cart
First insert a 10-24 x 1" hex head screw through the plastic mounting plate. Next use
two 10-32 flat head x1/2" long screws to mount the plastic mounting plate to the
Pasco cart. Finally, use the barrel bolt to hold the WDSS down on the mounting
plate. The process is shown in the series of photos below:
Mounting an Extra Mass on Top of the WDSS
For many dynamics cart experiments, it is helpful to be able to add mass to the cart.
The WDSS has been designed to allow you to mount one or two Vernier 0.5 kg
masses to the cart. These masses are Vernier order code MASS. The photos below
show one mass being installed. If a second mass is added, place it next to the first
one, toward the force sensor. It is bolted down in the same way.
The hole for bolting down the mass is not symmetrical to the mass. If the mass does
not appear to be square to the WDSS, flip the mass over to correct the problem.
