Forces and Newton II
Elias Ghantous
PHYS 151 – Section NQ
Thursday 10:10am
Hasbrouck Lab Room 214
October 13, 2017
Abstract
In this experiment, I studied how forces cause an object to accelerate. I also studied the relationship between force vectors, mass and acceleration. Gathering of data took place through the use of a force table and a PAScar track system.
Questions & Answers
1.For both the 1st and 2nd labs, we had objects that were “falling” (a golf ball for lab 1 and the hanging mass for lab 2). Was the acceleration of both objects constant? An object in free fall has constant acceleration. Were the two objects (golf ball and hanging mass) in free fall? Explain why or why not. (2 points)
The acceleration for the golf ball was constant,
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(Assume the friction between the air track and PAScar is negligible) (2 points)
5.What is the expression for the net force on the PAScar? Answer the same question for the hanging mass. Finally, what is the net force on the system as a whole (PAScar plus the hanging mass), and which of the three net forces that you found equals the tension in the string connecting the PAScar to the hanging mass? (2 points)
For the PAScar, gravity is cancelled out by the normal force so we only have force in the horizontal direction from the tension, Fcar = Fx. For the hanging mass, we only have forces in the vertical direction, Fmass = Fy = mg. The force on the system as a whole would be
Fsystem = √[(Fx)2 + (mg)2]. Fsystem is the net force that equals the tension in the string that connects the PAScar to the hanging mass.
6.List your data from the PAScar/hanging mass experiment and state your experimental value for the gravitational acceleration. Calculate the percent error for your measured value of g. Finally, state three sources of error for the PAScar/hanging mass experiment. List errors that are unique to this experiment, i.e. human, calculation, system, computer, sensor, or any other nondescript/general error will not receive credit. (2
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g
5g 0.019 0.1986 0.001 10.1
10g 0.038 0.354 0.0018 9.2
15g 0.056 0.516 0.0027 9.12
20g 0.074 0.68 0.0033 9.18
Errors that may have occurred may be neglecting friction between the car and the track and also the distance from which the car was let go from may be inconsistent.
7.Suppose the string connecting the PAScar and the hanging mass is suddenly cut. Describe explicitly for both the hanging mass and the PAScar what the velocity and acceleration will be before and after the string is cut. (Assume the friction between the air track and PAScar is negligible) (1 point)
Once the string is cut the PAScar will continue to move on the track with a constant velocity and no acceleration. The hanging mass would be in free fall and its acceleration would be that of gravity.
Conclusion
With the use of vectors and the force table, I was able to balance the ring in the middle of the table, and figure out what components were necessary to cancel out all the forces that were acting upon it. The PAScar system allowed me to calculate the acceleration of the car with different weights of hanging mass