Newton 2nd Law 1

  Newton 2nd Law! By: Wanwarisa Krittiyasrisumet

Advanced Placement Physics Ms. Susana Alulod Mahidol University International Demonstration School Semester 1 Academic Year 2018-2019

OBJECTIVE Objective of this experiment is to demonstrate Newton’s second law and to proof that mass of the object is unnecessary when finding acceleration.

INTRODUCTION      Force is a push or pull action upon the object that has interaction with another object. Force is a vector quantity that is measured in a standard unit, Newton.      There are three motion laws of Newton. First law is the “Law of Inertia,” saying that the uniform motion of the object will remain the same if there is no external force inserted. Therefore, the equation for Newton’s first law is F=0. The Second law is F=ma,meaning that acceleration and mass is related to applied force. Last one is Newton’s third law. It is said, “action equals reaction”. This means that for every action there is an equal and opposite force.

MATERIALS Stopwatch

Track

Cart

Inclined plane stand

Meter Ruler

Sponge

PROCEDURES 1. Set up the experiment by placing the track on the stand. 2. Mark the distance at 80 cm and 140 cm, so that the distance is 60 cm apart from each other. 3. Place the cart on the track and make sure that it begins at 20 cm (X0 = 20 cm). 4. Measure the slated distance and the height of the stand to calculate the angle of the incline plane. 5. Release the cart and simultaneously press start on the stopwatch. 6. When the cart reaches the 60 cm point, press the ‘lap/reset’ button on the watch to get the instantaneous time. 7. Then press the start/stop button when the cart reaches 140 cm point. 8. Record down the data. 9. Repeat step 3 - 8 to collect the data for the other trials.

DATA AND RESULTS Start at 20 cm (X0 = 20cm)

DATA AND RESULTS CALCULATION :

ANALYSIS      There are some differences in the results from both calculations; Newton’s 2nd law and kinematic. At the first 60 cm distance, acceleration from using kinematic equation is 1.174 m/s2, but the acceleration from Newton’s 2nd law is 0.98 m/s2. The error is depend upon the time recorded for all the five trials. This is caused by human error, which is the speed of the person who press the stopwatch, therefore, time varies for each trial.      The same mistake takes place at 120 cm too. The acceleration of the cart should be the same throughout its travel, but the result we get is contrasted with the fact. At 120 cm, the calculated result is 1.096 m/s2, which is not the same with acceleration at 60 cm: 1.174 m/s2. This is because the time measured is not accurate due to human error.

RECOMMENDATION

To improve for the next experiment, I think we should try and change the person who control the stopwatch or let each person press the stopwatch for each trial, so that we can get the variety of time and accuracy of different people. We can also do more trials and when the result is averaged, it’s going to be more precise.

CONCLUSION In conclusion, the acceleration of the moving object down the inclined plane doesn’t depend on the mass of the object. Because the mass cancelled out on both side of the equation, mg sin θ = ma, the only thing that is matter in finding the acceleration of the object is the gravity and the angle of the incline. Therefore, the equation is left with g sin θ = a.

REFERENCES - Newton's Three Laws of Motion. (n.d.) Retrieved from: http://www.pas.rochester.edu/~blackman/a st104/newton3laws16.html - Physics Classroom. (n.d.) The Meaning of Force. Retrieved from:https://www.physicsclassroom.com/cl ass/newtlaws/Lesson-2/The-Meaning-ofForce