' Chrome File Edit View History Bookmarks Profiles Tab Window Help u SunMarZO 7205PM . m Lab 5 , Acceleration & Measi X Bl) 39419847 X * Homework Help , Q&A from X + V C learnus-east-1-prodfleet02-xythos.contentblackboardcdn.com ;' w I 5 Reading List 39419847 Pumas 1 To understand acceleration by measuring the acceleration of an object. To measure the acceleration due to gravity. Introduction: Background: The air track is a device that allows a metal car to move in a straight line along a track with reduced friction. The air track relates to some of our daily experiences with motion. For example, when a bus drives along a straight road, the bus can (or should) only travel forward or backward, just like the car on the air track. A subway traveling on a straight path is another example of motion in a straight line. In addition, there is very little friction in the wheels of a bus or a subway. much like the case of the air track. Next time you are on a bus that is speeding up or slowing down, remember the air track! The main difference between a bus or a subway and our air track is that there is no engine or brakes in the air track. Gravity does all the work for us. This allows us to measure acceleration without worrying about too many forces. When the track is tilted at an angle, the metal car will accelerate down the track. The two photo sensors sense when the car has passed, and they turn a digital timer on and off. Thus, we can measure how much time the car spent in its acceleration from one sensor to the other. Using this time we can calculate the acceleration along the track. Once we calculate the acceleration, our job is done! How do we know if our accelerations are correct? What is a typical value? Keep in mind that the acceleration due to gravity is 9.8 m/sz. Would you expect the acceleration of the car to be more or less than the acceleration due to gravitY? How much more or less? Try to estimate your result. Once we think we have a reasonable value for acceleration, we can relate this value to the acceleration due to gravity 9, as described below. This will give us a number to which we can compare our result. Remember that calculating g is only a secondary purpose to this lab. There are many better ways to measure 9 in the lab. WhY? Try to think of some better ways, and feel free to offer suggestions! Since this is not the best way to measure g, we do not expect the percent difference to be very close to zero. The percent difference will give us an idea of whether we are at least in the ballpark. Mateo ac-n @uaZmereme ' Chrome File Edit View History Bookmarks Profiles Tab Window Help u SunMarZO 7205PM . l'rl~ Lab 5 , Acceleration & Measl X Bl) 39419847 X * Homework Help , Q&A from X + V C learnus-east-i-prodfleet02-xythos.contentblackboardcdn.com ;' w I 5 Reading List 39419847 or a subway, much like th air track. Next time you are on a bus that is speeding up or slowing down, remember the air track! The main difference between a bus or a subway and our air track is that there is no engine or brakes in the air track. Gravity does all the work for us. This allows us to measure acceleration without worrying about too many forces. When the track is tilted at an angle, the metal car will accelerate down the track. The two photo sensors sense when the car has passed, and they turn a digital timer on and off. Thus, we can measure how much time the car spent in its acceleration from one sensor to the other. Using this time we can calculate the acceleration along the track. Once we calculate the acceleration, our job is done! How do we know if our accelerations are correct? What is a typical value? Keep in mind that the acceleration due to gravity is 9.8 m/sz. Would you expect the acceleration of the car to be more or less than the acceleration due to gravity? How much more or less? Try to estimate your result. Once we think we have a reasonable value for acceleration, we can relate this value to the acceleration due to gravity 9, as described below. This will give us a number to which we can compare our result. Remember that calculating g is only a secondary purpose to this lab. There are many better ways to measure 9 in the lab. Why? Try to think of some better ways, and feel free to offer suggestions! Since this is not the best way to measure 9, we do not expect the percent difference to be very close to zero. The percent difference will give us an idea of whether we are at least in the ballpark. The details: It can be shown fairly easily that the acceleration due to gravity is related to the acceleration along the track by a _ sin 6 where g is the acceleration due to gravity and is equal to 9.8 mlsz, ' Chrome File Edit View History Bookmarks Profiles Tab Window Help . l'rl~ Lab57Acceleration8Measi X Bl) 39419847 x k Homework He|p70&Afrom X + C' Iearnus-east-1-prodf|eet02-xythos.contentblackbcardcdn.com 39419847 and Bis the angle of the track. It is beyond the scope of this lab to derive the above expression. However, scientists often use results from previous work and do not always fully understand how those results were derived. Scientists must be careful to use results from trusted sources and also to see if those results make sense. Does the above result make sense? We can nd out for ourselves if we see how 9 is related to a for an angle of zero degrees. How about for an angle of 90 degrees? Is the relationship between 9 and a what you expect in each of these cases? (Note: sin(0) = 0, and sin(90) = 1.) We can relate sin9 to some measurements in the experiment as follows: sin9= L where H is the height of the stack of blocks placed under one side of the air track. and L is the distance between the support legs of the air track. So now the relationship between 9 and a is quite simple: (Again, try to see if that result makes sense. What happens to a if you change H?) The acceleration along the air track is given by the equation of motion d = 1at2 2 where d is the distance between the photo sensors, and t is the time it takes for the car to travel between the sensors (assuming that the car starts its motion right at the photogate sensor). Solvin- this e-uation for a, we get: $0, ifwe know the quantities L, and d, and we measure the time tfor each height H that we use, we can calculate a, and then we can calculate g to check our result. Chrome File Edit View History Bookmarks Profiles Tab Window Help O . Q g Sun Mar 20 7:06 PM Bb Lab 5 - Acceleration & Measure X Bb 39419847 Homework Help - Q&A from Or x + -7 C learn-us-east-1-prod-fleet02-xythos.content.blackboardcdn.com/61aab133e7df2/39419847?X-Blackboard-Expiration=1647831600000&X-Blackboard-... Reading List E 39419847 2 / 5 100% + air track photo sensor blocks _d 4 - 0 2 Remember: To convert from centimeters (cm) to meters (m), divide by 100. To convert from millimeters (mm) to meters (m), divide by 1000. percent difference = lexperimental value - known value| x 100 3 known value) Air track operation: You may turn the air off when the air track is not needed (otherwise the room gets too noisy). 20 atli 4' Chrome File Edit View History Bookmarks Profiles Tab Window Help . l'rl~ LabSeACceleration8Measi X Bl) 39419847 )