1. Virtual Lab: Exploring Newton’s 2nd Law

2. What to Do:
To accomplish this virtual lab, you will need to read through the procedure so that you understand what was done in the lab. Then go through the following slides and record the data for your lab.

3. Experiment 1
Step 1: see pictures

4. Experiment 1
Steps 2 and 3: see picture

5. Experiment 1
Step 4: The mass of the cart is 250 g (you will need to convert this value into kg!)

6. Experiment 1
Step 5: See picture. We did not need to use a reflector for the sensor.

7. Experiment 1
Step 6: See picture.

8. Experiment 1
Step 7: See picture.

9. Experiment 1
Steps 8 and 9: The cart was set in place and then let go. The force on the end of the string pulled the cart forward and the motion detector measured the position and velocity of the cart as it moved.

10. Experiment 1 Definition Time:
Force = the mass on the end of the string pulling the cart; units are “Newtons”; the force must be measured with a spring scale
Mass = the total mass of the entire system (cart, hanging mass, and mass on the cart); units are “grams” and must be converted into kilograms
Acceleration = the change in velocity of the cart; units are m/s2; the slope of the velocity-time graph is the acceleration of the cart

11. Experiment 1
Steps 10-12: The graph is shown in the picture below. The velocity-time graph is the bottom graph. We used the analysis tool on the LabQuest to determine the slope of the portion of the velocity-time graph when the cart was accelerating. The slope is shown in the second picture.

12. Experiment 1
Step 13: Different masses were then hung on the end of the string. The data for a 30 g mass hung on the end of the string is shown below.

13. Experiment 1
Step 13: Different masses were then hung on the end of the string. The data for a 40 g mass hung on the end of the string is shown below.

14. Experiment 1
Step 13: Different masses were then hung on the end of the string. The data for a 50 g mass hung on the end of the string is shown below.

15. Experiment 1
Step 13: Different masses were then hung on the end of the string. The data for a 60 g mass hung on the end of the string is shown below.

16. Experiment 1
Step 14: To convert each mass on the end of the string into its weight, multiply the mass (in kg) by 9.8 m/s2. This weight is the force acting on the cart in each trial. (For instance, the first trial you did used a 20 g mass on the end of the string. The weight of this mass is kg x 9.8 m/s2 = N.)

17. Experiment 1
Step 15: Now it’s time for you to complete the rest of this experiment. Experiment 2 will begin on the next slide.

18. Experiment 2
Steps 1-6: This is a very similar set up to the 1st experiment. However, in this experiment, the force (hanging weight) will remain constant while the mass of the cart will change. The hanging weight will be a 50 g mass on the end of the string for every trial.

19. Experiment 2
Step 7: Below is a position-time graph (top) and velocity-time graph (bottom) for the moving cart. (mass = 250 g) without any additional mass on it. The highlighted area (gray) is while the cart was accelerating when the hanging mass was pulling it.

20. Experiment 2
Steps 8-10: After analyzing the velocity-time graph during the acceleration, the acceleration was determined by calculating the slope of the highlighted section of the velocity-time graph. The slope (acceleration) is shown below.

21. Experiment 2
Step 11: The experiment was run again, this time with a 250 g mass added to the cart. The result is shown below.

22. Experiment 2
Step 11: The experiment was run again, this time with a 500 g mass added to the cart. The result is shown below.

23. Experiment 2
Step 11: The experiment was run again, this time with a 750 g mass added to the cart. The result is shown below.

24. Experiment 2
Step 11: The experiment was run again, this time with a 1000 g mass added to the cart. The result is shown below.

25. Experiment 2
Step 12: That’s it! Now just finish up the analysis and questions. Good Luck!!!