Determination of the Force of Gravity
Go to https://phet.colorado.edu/sims/html/gravity-force-lab/latest/gravity-force-lab_en.html
Qualitative Observations
1. How does the changing the separation of the objects affect the
force between them?
2. What happens to the force between the objects when mass 1 increases?
3. What happens to the force between the objects if Mass 2 decreases?
4. What is the ratio of the force on the blue object to the force on the red object? What if the mass of the blue one is twice as big as the red object? Explain.
5. What direction are the gravitational forces acting on the objects?
Quantitative
It is now time to build a model.
1. What THREE things can we change/vary?
2. Select an independent variable (IV) and dependent variable (DV) and constant (C)
a. DV:
b. IV:
c. C:
3. Collect 10 data points and graph the independent variable on the x-axis, and dependent variable on the y-axis. Paste a screenshot of your graph here:
4. Select a new independent and dependent variable and constant
a. DV:
b. IV:
c. C:
5. Collect 10 data points and graph the independent variable on the x-axis, and dependent variable on the y-axis. Paste a screenshot of your graph here:
6. Repeat the varying mass vs. force experiment, with a different value for the second mass.
a. What is your new value for the second mass?
b. How did the results of this experiment change as compared to the first trial?
Analysis
1. Explain why varying the second mass had the same effect on the force as varying the first mass.
2. What is the relationship between Mass and force? What happens to the force if you double the mass of the blue object? What happens to the original force if you then triple the red object’s masses?
3. What is the relationship between distance and the force of gravity? What happens if you triple the distance between the objects? Half the distance between them?
4. Combine your proportions between Mass 1 (m1), Mass 2 (m2) distance (r) into a single proportion to the
Force of gravity (Fg). Remember that this is an expression of proportionality, not an equation.
Show your instructor your above work before you continue.
5. Calculate the above proportionality for your lab data. Does it equal Fg? Also work out your units, do they equal a unit of force?
6. Make a graph of Force vs. your proportionality expression from (4) and paste it here.
7. What is the numerical value of the slope? What are its units? What does the slope represent?
8. Determine units for the the gravitational constant (G) that will be make the equation dimensionally consistent
9. Write your full formula and check with your instructor.
Conclusions
Summarize the experiments that were performed, the data that was taken, and any conclusions that were reached.
