Taring the Force Sensor
To tare (zero) the sensor, press the Tare button on the side of
the sensor. This will set the voltage from the sensor to
approximately zero volts. You must always tare the Force
Sensor before taking measurements. Always tare the Force
Sensor in the exact orientation in which it will be used.
You can also tare the sensor while a force is applied to the
sensor. For example, if you want to measure the change in force
instead of absolute force values during an experiment, set up
the experimental equipment as needed and tare the sensor at
the beginning of the experiment before taking data. The sensor
can maintain its "zeroed" condition for over thirty minutes before
needing to be tared again.
You can verify the tare procedure by monitoring the force value
in PASCO Capstone or SPARKvue and pressing the Tare button
while data is being collected.
Calibration
The Force Sensor is calibrated at the factory and does not
require calibration before use. The sensor is designed to
produce approximately zero volts when it is "zeroed", with a
change in force of one newton causing a change in output
voltage of 160 millivolts (0.160 V). This voltage can be converted
directly into force by simply dividing the voltage by 0.160. For
example, a voltage of 1.60 V is equal to a force of 10 N, a
voltage of -0.160 V equals a force of -1 N (in other words, a pull
of 1 N), and so on. Therefore, the sensor does not need to be
calibrated.
However, it is possible to calibrate the sensor for greater
accuracy. For instructions on calibrating the sensor, see the
PASCO Capstone or SPARKvue online help and search
"Calibrate a force sensor".
Suggested experiments
Experiment 1: Component of force on an
inclined plane
When a cart is at rest on an inclined plane, the component of the
force acting on the cart that is parallel to the plane is mgsin ,
where mg is the weight of the cart and is the angle of the plane
with respect to the ground. Use the sensor to measure the
weight (in newtons) of a dynamics cart. Mount the sensor in
place at the high end of the inclined dynamics track and connect
it via a string to the dynamics cart on the track. Measure the
angle of the track. Measure the tension in the string using the
sensor, and compare this to the theoretical value mgsin .
mg
mgcos
mgsin
Cart
Force
Sensor
Figure 1. Layout for Experiment 1.
Experiment 2: Newton’s Second Law -
Pushing and pulling a cart
When an object is accelerated by a net force, the acceleration is
directly proportional to the net force and inversely proportional to
the object’s mass. Mount the Force Sensor onto a dynamics
cart. Use a motion sensor, such as the Wireless Motion Sensor
(PS-3219), to measure the velocity and acceleration of the cart.
Zero the Force Sensor. By exerting force on the hook on the
front of the Force Sensor, move the cart gently but irregularly
back and forth in front of the motion sensor. Use SPARKvue or
PASCO Capstone to compare the measured force to the
measured velocity and acceleration.
Motion
Sensor
Force
Sensor
Cart
Figure 2. Layout for Experiment 2.
Experiment 3: Newton’s Second Law -
Constant force
What happens if the cart is pulled by a constant force? Arrange
the Force Sensor, your chosen motion sensor, and cart on the
track in the same way as Experiment 2. Set up a pulley, string,
and hanging mass so that the cart and Force Sensor will be
pulled by the string attached to the hanging mass, as shown in
Figure 3. Use the motion sensor to measure the velocity and
acceleration of the cart as it is pulled by the string. Use
SPARKvue or PASCO Capstone to compare the measured force
to the measured velocity and acceleration. Change the hanging
mass and repeat the experiment.
IMPORTANT: Do NOT allow the cart or Force
Sensor to collide with the pulley, as this may
cause damage to either component! Ensure that
the cart and sensor will be caught before
colliding with the pulley, either by hand or with
the aid of the Elastic Bumper (ME-8998) as
shown in Figure 3.
Mass
Motion
Sensor
Force Sensor
Cart
Pulley
Elastic Bumper
(ME-8998)
Figure 3. Layout for Experiments 3 and 4.
Experiment 4: The Work-Energy Theorem
(W = KE)
What happens to the kinetic energy of the cart as it is pulled by
a constant force? This experiment will be use the same physical
setup as Experiment 3 (shown in Figure 3). Use the motion
sensor to measure the change in position and the velocity of the
cart as it is pulled by the string. Using PASCO Capstone or
SPARKvue’s built-in analysis tools, find the area under the curve
of a force versus distance graph to find the work done on the
cart. Calculate the amount of kinetic energy gained by the cart
Product Guide | 012-05804D
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