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Newton’s Second Law 012-11003 r1.04 Newton’s Second Law Introduction Journals and Snapshots The Snapshot button is used to capture the screen. The Journal is where snapshots are stored and viewed. The Share button is used to export or print your journal to turn in your work. Each page of this lab that contains the symbol should be inserted into your journal. After completing a lab page with the snapshot symbol, tap (in the upper right corner) to insert the page into your journal. Note: You may want to take a snapshot of the first page of this lab as a cover page for your journal. Newton’s Second Law Lab Challenge What is the relationship between the net force applied to an object and its motion? Newton’s Second Law Background Fk Spring x0 = 0 Mass In Equilibrium Fg Like Newton, we will observe a simple system to look for a relationship between net force and motion. From earlier studies we know that a mass hung from a spring experiences a force due to gravity and a restoring force from the spring. In equilibrium the two forces are equal and opposite. When the mass is displaced one of the two forces is greater, thus causing a non-zero net force pointed towards the equilibrium position. We will investigate how this net force is related to the motion of the system. Newton’s Second Law a) Q1: In the box below, indicate which force is greater (spring or gravity) for both a) and b), then snapshot this page. b) ∆x1 x0 x0 ∆x2 Newton’s Second Law Materials and Equipment Collect all of these materials before beginning the lab. • Force Sensor • Motion Sensor • Springs • Rod Stand • Rod • Mass • Clamp Newton’s Second Law Sequencing Challenge A. Oscillate the mass on the spring, and begin collecting data. B. Plot net force measured by the force sensor versus acceleration. C. Use the linear curve fit to determine the slope of the line. D. Connect the Motion Sensor and the Force Sensor to the SPARK Science Learning System. The steps to the left are part of the procedure for this lab activity. They are not in the right order. Determine the correct sequence of the steps, then take a snapshot of this page. Newton’s Second Law Setup 1. Connect the Force Sensor to the rod and rod stand. 2. Hang the mass from the Force Sensor using the spring. 3. Place the Motion Sensor directly below the mass with the face of the sensor pointed up at the mass. 4. Connect the Force and Motion Sensor to your SPARK Science Learning System. Newton’s Second Law Collect Data 1. With the mass hanging motionless, press the ZERO button on the force sensor. 2. Pull down gently on the mass and release to start it moving up and down. 3. Tap data. to start collecting 4. After the mass has finished three to four complete cycles (~5 to 10 seconds), tap to stop data collection. Newton’s Second Law Analysis 1. Why do you think it is important to press the ZERO button before collecting data? a) to calibrate the Force Sensor b) to ensure the Force and Motion Sensor both start from the same point c) to make sure no forces are present d) to ensure the Force Sensor is measuring the net force on the mass Make your selection below then take a snapshot of this page. Newton’s Second Law Analysis While collecting data we observed the position of the object as it changed over time to ensure that enough data was collected and that the data and observed motion were consistent. Next we will compare force to motion. After each pair of graphs there is a question, you can go back to the graph if you need to compare a few points In time on each pair of graphs to determine the nature of their relationship. Newton’s Second Law Newton’s Second Law Analysis 2. Which description below best describes the relationship between force and position in the case of a spring and mass system? a) Force is proportional to position. b) Force is inversely proportional to position. c) Force is unrelated to position. d) Force is negatively proportional to position. Make your selection below then take a snapshot of this page. Newton’s Second Law Newton’s Second Law Analysis 3. Which description below best describes the relationship between force and velocity? a) Force is proportional to velocity. b) Force is inversely proportional to velocity. c) Force is offset from velocity. d) Force is negatively proportional velocity. Make your selection below then take a snapshot of this page. Newton’s Second Law Newton’s Second Law Analysis 4. Which description below best describes the relationship between force and acceleration? a) Force is proportional to acceleration. b) Force is inversely proportional to acceleration. c) Force is the inverse square of acceleration. d) Force is negatively proportional to acceleration. Make your selection below then take a snapshot of this page. Newton’s Second Law Analysis During data collection we observed the position of the object as it changed over time to ensure that enough data was collected and that the data and observed motion were consistent. On the following graph we will plot force versus acceleration to better understand the nature of the relationship between these two variables. Newton’s Second Law Analysis 5. In the space below, describe the shape of the data plot of force versus acceleration. Then take a snapshot of this page. Newton’s Second Law Analysis 6. Apply a linear curve fit to the force versus acceleration plot, then take a snapshot of this page. *To Apply a Curve Fit: 1. Tap to open the tool palette. 2. Tap to open the Curve Fit screen. 3. Tap the name of the curve fit required. Newton’s Second Law Analysis 7. Indicate any relationship that the slope of the curve fit line from the previous page has with the experiment, and then take a snapshot of this page. Newton’s Second Law Analysis 8. Using your knowledge of graphing, how would you express the equation of the line from the Force versus Acceleration graph in terms of the variables of this experiment? Below the equation write out the units of each variable to be sure the equation is balanced. Newton’s Second Law Synthesis 1. The harder a ball is thrown (apply more force), the faster it will move (greater initial velocity resulting from acceleration). If you throw a 1 kg softball as hard as you can and it is traveling at 20 m/s when it leaves your hand, how fast will a 5 kg shot put travel with the same throw? Newton’s Second Law Synthesis 2. Force is proportional to acceleration. Given the answer to Synthesis question 1, how would you describe the relationship between acceleration and mass? Newton’s Second Law Synthesis 3. If we launch a rocket that has been designed to produce a constant force, will the acceleration at initial launch be the same as the acceleration just before the fuel is completely expended? Newton’s Second Law Synthesis 4. A similar experiment is set up so that a force sensor is used to drag a 1.5 kg brick across a table while a motion sensor measures its acceleration. Several trials are conducted, but the slope of the force versus acceleration graph is consistently about 2. What would explain the difference? What would you do to improve the results? Newton’s Second Law Multiple Choice Question 1. If two potatoes are launched from a potato launcher that applies the same force, a) the heavier potato will be traveling faster than the lighter one. b) the lighter potato will be traveling faster than the heavier one. c) regardless of their mass, they will be traveling at the same velocity. d) there is not enough information to draw a conclusion. Make your selection below then take a snapshot of this page. Newton’s Second Law Multiple Choice Question 2. A roller coaster is designed to deliver 3g of acceleration at the bottom of a loop. The mass of the cart is 500 kg and the rider is 100 kg. If the track is designed to withstand 15,000 N of force without buckling, will the cart and rider make it through the loop? a) No, this ride will likely end in disaster. b) Yes, the cart and rider will easily make it past the dip. c) Yes, but a second rider of equal size would not make it through. d) There is not enough information to draw a conclusion. Make your selection below then take a snapshot of this page. Newton’s Second Law Multiple Choice Question 3. A 1000 kg rocket is launching with its engine producing a force of 39240 N. What is its acceleration? a) 9.81 m/s2 b) 39.24 m/s2 c) 1000 m/s2 d) 29.43 m/s2 Make your selection below then take a snapshot of this page. Newton’s Second Law Multiple Choice Question 4. The acceleration of an object is ___________ a) proportional to the mass of the object and the force being applied. b) proportional to the mass of the object, and inversely proportional to the force being applied. c) proportional to the net force being applied and inversely proportional to the mass of the object. d) always perpendicular to the force of gravity. Make your selection below then take a snapshot of this page. Newton’s Second Law Multiple Choice Question 5. The net force on an object is ______________ a) proportional to the force of gravity. b) the vector sum of the individual forces acting on the object. c) always balanced by the normal force. d) both A and C. Make your selection below then take a snapshot of this page. Newton’s Second Law Congratulations! You have completed the lab. Please remember to follow your teacher's instructions for cleaning-up and submitting your lab. Physics Template References ALL IMAGES WERE TAKEN FROM PASCO DOCUMENTATION, PUBLIC DOMAIN CLIP ART, OR WIKIMEDIA FOUNDATION COMMONS: http://commons.wikimedia.org/wiki/File:USAF_F-16C_Profile.JPEG http://commons.wikimedia.org/wiki/File:Damped_spring.gif http://commons.wikimedia.org/wiki/File:Launch_of_Space_Shuttle_Atlantis.jpg http://www.freeclipartnow.com/office/paper-shredder.jpg.html