Objectives: To study newton’s Second Law for a given system of masses using the computer to determine acceleration. Apparatus: Science Workshop Interface, laptop, USB drive, rod stand to raise track, dynamics cart, ±50 Newton force sensor, mass set with hanger, smart pulley with table clamp, track, string, meter stick.
In this activity, a smart pulley will measure the motion of the cart on one side that will be pulled by a string on the other side of a pulley.
One side of the string will be attach to a mass and suspended over a smart pulley.
On the cart, there will be a force sensor mounted on the cart which will measure the force that accelerate the cart (it is also a string tension) and will be compared with theoretical string tension.
We will use a program called Data Studio which calculates the velocity of the moving cart as a function of time.
The graph that will be created in the Data Studio program will be velocity versus time, it reveals the cart’s acceleration, which will be compared to the theoretical value.
We will plug in the force sensor into analog channel A and the smart pulley into digital channel 1 on the Science Workshop Interface.
Now, connect the Science Workshop Interface with the laptop using a UBS cable.
Plug the power supplies into the interface box and the laptop.
Turn on the interface box and the laptop.
Go to desktop and double click the CLC Physics Experiments folder, and then double click ‘Newton’s Second Law Experiment.ds.’
Now, we will have to calibrate the force sensor following these steps:
1. Open the Experiment Setup Window.
2. In the Experiment Setup Window, click the “Calibrate Sensore……” button and select the Force Sensor. In the “Calibration Type” choose the 2 point. The “Calibrate Sensors” window will show the default calibration values. The force sensor is set up so that a pull away from the sensor is a ‘negative’ force.
3. Using a small screw driver mount the force sensor on the cart. Do Not put the sting on force sensor’s hook right now.
4. To make a Calibration Point 1, hang a .1kg mass on the end of the sting and pass the string over the pulley. Now, connect the other end to the hook on the force sensor. Total mass of the hanging will be .105kg. Hold the cart and sensor stationary, do not move it. The weight of the hanging mass is the string tension.
5. For calibration point 1 click on the “Read” button. Put in the weight in Newtons of the hanging mass (kg*9.8N/kg). Enter the object’s weight as a negative value (it’s a force pulling away from sensor). Click “OK” to return to the Experiment Setup Window.
6. To make a Calibration Point 2, press the tare button on the side of the force sensor to zero the sensor. Click on the “Read” button for Calibration Point 2. Since there will be no object on the sensor’s hook, type 0 Newtons.
Find the mass of the cart + force sensor.
Now set the cart with the force sensor on the aluminum track horizontally with the sting hooked to the cart.
Hold the cart against the pulley end of the track so that the red light on the smart pulley will be on, and then when you are ready to take data, click on the START button, be ready to click the STOP button right before catching the cart so it does not collide with the smart pulley.
Take the data value of the acceleration (slope of v vs. t graph) for the data range showing a constant acceleration (it will be done by highlighting the region of interest on the graph). Take the mean force (T) data and record it, from the same time range using the F vs. t graph, and compare it with the acceleration, a, and tension, T, with the theoretical values.
Use the scroll bar in the table menu to see all the data.
If you have pressed the START button before releasing the cart you will need to highlight the middle section of force data in the table to get the mean tension, appearing at the bottom of the table menu, when the system was accelerating. Part B: