Sasha Cruz - Lab 4 Forces and Motion QMPHYS1115 Rev9.2.2023

Lab 4: Forces and Motion © 2023 by Orlando Patricio adapted from https://phet.colorado.edu/en/simulations/category/physics Name: Sasha Cruz INSTRUCTIONS: (1) Download this lab document, CLICK on “ enable editing ” located at the top, middle of the downloaded document and type out answers on the space provided for then save your answers. (2) If the spacing automatically moves, adjust so that your answers are not all over the place. (3) Upload this document, with your answers on it, on the designated Lab 4 Dropbox on Canvas Lab Reports/Module Tab. (4) If possible, ALL answers must in green font or highlighted in green. Do NOT delete anything in this lab document. Grading Policy for Lab Reports WITH Pre-/Post-lab Questions Grading Policy for Lab Reports WITHOUT Pre-/Post-lab Questions Completeness and accuracy of answers (with required screenshots) for the: 1. Warm-up and lab activities – 70% 2. Pre-/Post-lab questions – 10% 3. Conclusions and real-life applications – 20% Completeness and accuracy of answers (with required screenshots) for the: 1. Warm-up and lab activities – 80% 2. Conclusions & real-life applications – 20% This lab uses the Forces and Motion simulation from PhET Interactive Simulations at University of Colorado Boulder under the CC-BY 4.0 license. Purposes/Objectives: In this lab, you will be able to: 1) explain that net force is the sum of forces acting on an object. 2) explore how the sum of forces or net force can change motion. Procedure: 1) Click the link below (hover mouse on the link then press at the same time: ctrl and left click ) http://phet.colorado.edu/sims/html/forces-and-motion-basics/latest/forces-and-motion- basics_en.html A. PhET Sim Introduction: 2) Play with the Net Force , Motion , Friction screen or tab for a few minutes. How does the Friction screen or tab differ from the Net Force and Motion screen or tab ? The Friction tab focuses on the force that opposes the motion of an object, which is represented by the interaction between the object and the surface it's moving on. It displays forces, values, masses, and speed. The net force tab has sum of forces, values, and speed while the motion tab has force, values, masses and speed,

3) What is something new you discovered? B. Develop your understanding: 4) Imagine that your friend, Sam is trying to move a box. Explore the free-body diagrams or FBDs in each picture or set-up below. Use the FRICTION TAB. Inside the FRICTION tab at the top, right corner, check off Sum of Forces , Values, Masses, and Speed. Forces with an arrow pointed to the right is already checked off. Note: To take a screenshot, click on one of the FBDs (from PHET sims) you want to screen capture then open this lab document and position the cursor where you want the screenshot to be pasted and then click on Insert (next to Home ). Look for Screenshot (below References ) then click on Screen Clipping on the window that appears. The picture drawing or one of the FBDs (select one FBD at a time) will show and highlight the area (by dragging the cursor) you want to clip/screenshot. The clip image will appear on this lab document where the cursor was positioned earlier. You may edit or position the picture drawing as you want it. Do the same procedure for the other picture drawings or screenshots. Figure 1. Figure 2. Figure 3. a) Paste below YOUR OWN SCREENSHOTS of the Force Diagrams (FBDs). That even if you apply the same equal force opposite an initial force and zero the sum of forces, that the momentum albeit slower will still pull in the direction of the initial momentum and only when you apply a force greater you will have the momentum stop and move in the opposite direction . Figure 1 in PhET Sim Friction Tab: In here, Sam is NOT pushing the box yet.

b) describe/define Applied Force . 7) Have Sam try to move the refrigerator. (In the PhET Sim, select the Friction screen or tab then drag and drop the refrigerator on the track. Remove the wooden crate/box, if necessary .) a) What is different from pushing the box? Use the PhET Sim to have a better visual understanding. (SET Friction slider should be NONE or close to ZERO to make it work). Applied force is the amount of force one “applies” to an object. The refrigerator is heavier than the box.

Note: Check-off the control panels like the one below then adjust the slider to increase the Applied Force.

c) Were you able to move the refrigerator? If not, what would you have to change? Describe what you did. 8) Try pushing other things, such as boxes; you can even stack them. What have you discovered? 9) Can you find different ways to make the Sum of Forces (net force) arrow change? a) List at least two. b) In your own words, what is Net Force ? The sum of all forces acting on an object. By applying more or less friction force once an applied force is applied. That as you increase the weight of an object, you’ll require more applied force to move the object and or less friction force. I was not able to move the refrigerator with just increasing the amount of applied force as the refrigerator weighed 200kg and the maximum amount of force applied was 500n. Only when I decreased the amount of friction force was I able to move the refrigerator.

10) What are some ways you can change the speed? 11) Using your answers from #10, what general statement can you make about the relationship between net force and how fast an object changes its speed (acceleration). The net force on an object changes its motion, therefore, the greater the net force, the greater the acceleration. Decreasing friction force, applying more weight and increasing the amount of applied force.