Newton’s 2nd Law of Motion Lab

Purpose - To verify that Newton’s 2nd Law of Motion, Fnet=ma,is valid through two methods by:

Part A: graphing net force(Fhanging)versus acceleration(a) for a constant mass (with motion sensor and Pasco software)

Part B: comparing the acceleration found on the tape to the acceleration calculated using Fhanging=mtotala

Testable Question: What is the relationship between Force and Acceleration when mass is held constant?

Part A:

Materials:

Laptop with PASCO Capstone software

Motion sensor

Lab cart

Pulley

String

Masses

Procedure:

Procedure

1.Connect the Motion Sensor to a computer. Put the range selection switch on the top end of the Motion Sensor to the (cart) setting.

2.Open PASCO Capstone program. Click on Text & Graph.

3.Click on to set y- and x- axes to position and time.

4.Place the Motion Sensor on one end of the track.Adjust the alignment knob on the side of the Sensor so that it points parallel to the track. Clamp the pulley to the other end of the track. Place this end over the edge of the table.

5.Determine the total mass of the lab cart and masses.

6.Attach a small mass to the end of a string and place the other masses on top of the lab cart.

7.Please have one person stop the cart before it rolls off the table!!!!!!!!!

Press Record to start recording data.

NOTE: Be sure to move your hands out of the way as soon as you release the cart.

8.If you are not satisfied with the data click on and start over the recording.

9.Save the file with the run and email it to yourself or save on your own device.To open the file on a new computer – double click on the file and Capstone software will open it.

10.Record position vs. time and velocity vs. time graphs for the motion of the lab cart pulled by the falling mass.

11.Determine the acceleration of this motion from a velocity-time graph.

12.Repeat steps 6-11 increasing the falling mass. To do that, you will remove various combinations of weights from the cart and hang them from the pulley, leaving the rest of the weights in the cart to keep the total mass (m) constant.

13.Collect your Data in a table Similar to the one shown here:

Falling Mass / Force Provided (N) / Acceleration of system (observed) (m/s2 ) / Acceleration of system (predicted/calculated) (m/s2 )
50gr
100 gr
150 gr
200 gr
…

14.Use Newton’s second Law to predict the acceleration the Lab cart will experience with each falling mass.

15.Determine the percent difference between the predicted and observed accelerations.

16.Move to part B.

Part B:

Materials:

Ticker tape and Ticker timer

Pulley wheel, Clamps

Ruler

Cartand String

Set of masses

Procedure:

  1. Set up equipment as shown in diagram.
  2. Find the mass of the cart and the total mass of the weights used

ticker timer weights

pulley wheel

Ticker tape cart

  1. Please have one person stop the cart before it rolls off the table!!!!!!!!!
  2. Insert ticker tape into the ticker timer. Turn on ticker timer and let the cart go at the same time.
  3. Shut the timer off as soon as the cart stopped.
  4. Ignore the first group of dots that are too close together to differentiate, and draw an arrow pointing to the first clear dot. This dot corresponds to time 0.00 seconds.
  5. The frequency of the Ticker timer is 1/60 s., so the interval between dots is 1/60 seconds, that is 0.0167sec. The quick way to find the acceleration will be pick the number of dots ( for example 6), measure a distance traveled during this time.

Time taken = 6 x 0.0167=0.1s

Distance traveled= 2.8 cm = 0.028m

Speed =d/t

Average Speed1 = 0.028/0.1=0.28m/s

Next 6 dots:

Time taken = 6 x 0.0167=0.1s

Distance traveled= 4.9 cm = 0.049m

Average Speed2 = 0.049/0.1=0.49m/s

( we have used 0.1 for changes in time because between the middle of the first interval and the middle of the second interval is 6 dots as well, which is 6x0.0167 = 0.1)

  1. Calculate the acceleration of the system using Newton’s law. Compare calculated and measured results.

Name ______

Lab Partner______

______

______

Newton’s 2nd Law of Motion Lab

Discussion - Explain what Newton’s 2nd Law of Motion. ______

Part A

Falling Mass / Force Provided (N) / Acceleration of system (observed) (m/s2 ) / Acceleration of system (calculated) (m/s2 ) / % difference

D-t graph 1 V-t graph 1 Acceleration calculation form the graph

D-t graph 2 V-t graph 2 Acceleration calculation form the graph

D-t graph 3 V-t graph 3 Acceleration calculation form the graph

D-t graph 4 V-t graph 4 Acceleration calculation form the graph

2. Calculations of acceleration from the Newton’s law.

FBD

3. Calculations of the percent error:

4. Conclusion: What is the relationship between acceleration and Fnetif mass is held constant??

Part B.

  1. Calculations of acceleration using the ticker tape.
  1. Calculations of acceleration using the Newtons Law.

FBD

  1. Identify sources of error that would make your results different than the expected.