Lab 5 Newtons 2nd Law

Fall 2021 Lab 4 LAB 5: NEWTON’S 2 ND LAW Fall 2021 Final Score: _________ / 100 pts This is the companion worksheet for the lab. This is not a replacement for the step-bystep walkthrough contained in the Lab Manual, rather it is a place to write your data and answers. You may fill in your answers on this sheet digitally or handwritten on paper. This assignment is due DIGITALLY on Canvas on the same day as the lab, at 11:59 PM. NAME: Reuben Fortier & Kayla Jackson SECTION: 801 Introduction What is the Objective for this Lab? Briefly summarize the theory behind the lab, including any relevant equations. (10 pts) The objective of this lab is to gain a better understanding of Newton’s Second Law. In the first part, we find out what happens to the acceleration of an object when the mass is kept constant, but the net force applied to the object is increased. In the second part, we examine the acceleration of an object when the net force is kept constant and the mass of the object is changed. To do this we will be using a cart on a level track attached to a pulley on which weights can be hung, along with a motion sensor to track the velocity of the cart over a time period. The theory behind the lab states that as long as a net force acts on an object, the velocity of that object will change. The greater the force, the greater the acceleration – they are directly proportional so that twice the force would result in twice the acceleration. Mass is inversely proportional to acceleration – twice the mass would result in half the acceleration for a given force. Equations: a = Fnet/m a ∝ Fnet a ∝ 1/m 1 Fall 2021 Lab 4 2 Part 1 – Constant System Mass 1. Hypothesis – Make an educated guess. Suppose a ball is projected horizontally. a. What happens to an object when you apply a net force to it? (2 pts) It accelerates proportionately to the force and moves in the same direction as the applied force b. What happens to the motion when you change the magnitude of that net force? (2 pts) The acceleration changes by the same magnitude Part 1 Results Mass of the Empty Cart = [kg] Run Mass of the Cart + Any Masses [kg] Mass of hanger [kg] Net force [N] 1 2 3 (15 pts) Measured acceleratio n [m/s2] Calculated Accelerati on [m/s2] % Differen ce Fall 2021 Lab 4 Include a snapshot of one of your runs. Be sure to include the linear fit in this picture! (5 pts) 2. What did you observe about the slope of the Linear Fit as the net force increased but the total mass was kept constant? (3 pts) The slope increased. 3. Why did the slope change for each run? (2 pts) The slope represents the acceleration, which increased as the net force applied increased. 3 Fall 2021 Lab 4 4. What variable(s) did you keep the same from one run to the next? What variable(s) did you control? (3pts) Total mass stayed the same, net force was the variable we changed. 5. What variable changed as a result and what was the response? (2 pts) The acceleration changed as a result of changing the net force. The response was for the acceleration to increase as the force increased. Using the fact that g = 9.81 [m/s2], along with your data in the Part 1 Results table, Calculate the theoretical acceleration by using Newton’s 2nd Law of Motion. Put your answers in the Table. Using that information, calculate the percent differences between the measured and theoretical acceleration value. 6. How do your results compare to your hypothesis? (2 pts) The results agree with the hypothesis. 7. What happens to an object's acceleration if the net force applied to the object is increased but the object's mass remains constant? (3 pts) The acceleration will increase. 8. Is the object's acceleration proportional to the net force? (2 pts) Yes. 9. Based on Newton's Second Law, predict what will happen to a Space Shuttle's acceleration after lift-off as it burns its fuel and loses mass. (3 pts) 4 Fall 2021 Lab 4 As the Space Shuttle loses mass, its acceleration will increase, as acceleration is inversely proportional to mass 10. Extension Problem (5 pts) Two people are pushing a mass 2.0 kg cart with forces F1 and F2. When the two forces push in the same direction, the net acceleration is 1.50 m/s/s. When each push in opposite directions, the net acceleration is 0.50 m/s/s. What are the magnitudes of the forces F1 and F2? 1m/s/s and 0.5 m/s/s Part 2: Constant Net Force 11. Hypothesis – Make an educated guess. a. What happens to the motion of an object if you increase the mass of the object but keep the net force constant? (2 pts) The acceleration decreases in an amount inversely proportional to the increase in mass. Part 2 Results Mass of the Empty Cart = [kg] 5 Fall 2021 Run Lab 4 Mass of the Cart + Any Masses [kg] Mass of hanger [kg] Net force [N] 6 Measured acceleratio n [m/s2] Calculated Accelerati on [m/s2] 4 5 6 (15 pts) Include a snapshot of one of your runs. Be sure to include the linear fit in this picture! (5 pts) 12. What did you observe about the slope of the Linear Fit as the total mass was increased but the net force was kept constant? Why did the slope change for each run? (3 pts) The slope decreased. The slope changed because the increased total mass caused decreased acceleration. % Differen ce Fall 2021 13. Lab 4 What variable(s) did you keep the same from one run to the next? What variable(s) did you control? (2 pts) Net force was kept the same (the mass of the hanger). Total mass was the variable we changed by adding mass to the cart. 14. What variable changed as a result and what was the response? (3 pts) Acceleration changed as a result of increasing the mass and the response was for acceleration to decrease as total mass increased. Using the fact that g = 9.81 [m/s2], along with your data in the Part 2 Results table, Calculate the theoretical acceleration by using Newton’s 2nd Law of Motion. Put your answers in the Table. With that information, calculate the percent differences between the measured and theoretical acceleration value. 15. 16. How do your results compare to your hypothesis? (2 pts) The results agree with our hypothesis. What happens to an object's acceleration if the net force applied to the object is constant but the total mass increases? (3 pts) The acceleration decreases. 17. Do your results agree with the idea that an object's acceleration inversely proportional to the total mass? (2 pts) Yes, the results agree with that idea. 18. What were the sources of error and uncertainty in this experiment? (3 pts) If something was wrong with the sensor, it would skew the results. We had to move to a different sensor because ours was not giving good data. The 7 Fall 2021 Lab 4 calculations don’t take into account air resistance, friction, room temperature, and other variables that could create uncertainty in the results. 19. Based on Newton's Second Law, predict what will happen to a truck's acceleration if it gains mass during a rainstorm but the net force on the truck remains constant. (3 pts) The acceleration of the truck will decrease an amount inversely proportional to the gained mass. 20. Extension Problem (5 pts) An unloaded sled with a mass of 12 kg has an acceleration of 2.3 m/s/s when it is pushed on a horizontal surface. What is its acceleration when it is fully loaded to a total of 25 kg, but the net force is the same? A = Fnet/m Fnet = am Fnet = 12kg * 2.3 Fnet = 27.6N A = Fnet/m A = 27.6N/25kg = 1.1m/s/s 8