Physics Lab Report for Motion

Lab report 2 Motion1+2

Introduction

This experiment contains three parts: part1 serves as a general introduction into Capstone software and motion sensor, which are useful tools in the following physics experiment work. To get familiar to their function, we will conduct basic measurements then check graph and digits displayed with our results; part2 is to learn graph reading on Capstone; part3, is about using Capstone to detect an accelerated motion of a glider on an inclined air track.

Materials & Methods

This series of experiments required computer software Capstone, which can output visual graphs of recent experiment. Through the connection of Smart Cart with the sensors required, it makes datas set up and analysis very quick and easy. Motion sensor was used in both parts of the process, by emitting and receiving sound pulses (sample rate can vary from1 to 250 Hz, depending on experiment requirement), it is able to record the motion time of experimental subject. Through further calculation, when applying current state’s sound speed into formula we are able to detect the position datas.

Part 1, was mainly about getting familiar with Capstone software. One blocker, a ruler meter and an intergration of the digital recorder mentioned above. Firstly, set all the parameters (sample rate 20Hz, data accuracy 3 significant figures). Use a meter ruler to measure the position of the blocker from motion sensor, to make sure the digits displayed consist to our measurement.

Kept the position stationary (0.7m), removed the blocker and replaced it with a A4-sized notebook. We moved the notebook in 3 different ways and match the motion type with time-velocity graph displayed. Several datas were recorded for calculating max&min velocity.

Part 2, was based on the ideal time-position and time-velocity graphs shown in textbook, with observation and judgement, we were required to do analysis and figure out several related questions.

Part 3, air track, 3 blockers, 2 gliders, motion sensor and Capstone were put into use. We operated on an accelerated motion of a glider on an inclined air track. Considering the air track to be frictionless, we could apply the knowledge of Newton’s 2nd Law, the magnitude of acceleration under this circumstance obey this equation, . Still, we first need to balance the possible friction. Then lifted the right side of the air track with 3 blockers, Measured the height of both side as well as the length of it. Calculated the angle from the following formula, . Obtained , we are able to compare theoretical acceleration to actual display on the Capstone to whether make confirmation or analyze possible error causes. Release glider from the upper side, keep a proper distance from the release point to motion sensor to secure its accuracy.

Using Capstone for graph display of three main quantities, position, velocity and acceleration , repeat the experiment above more than 3 times, then change its default setting to 25Hz to perform again. Select one best run and screenshot it.

Results

When checking capstone, we compared manual measurements to capstone’s calculations, there were always no perfect match. Within 0.7m, the datas from capstone were slightly less than ruler’s, but it turned opposite when position was greater than 1m. Also, the measurements from display differ greatly from time to time, so we assumed that the acoustic beam might not be receive correctly and reflected from elsewhere.Table1 compare measurements by ruler and capstone

In this case, the digit readings were farfetched when position was greater than 1m, so the position was controlled within 0.7m the following experiments. From our best run#9, two points were selected from slow slope and shape slope respectively. Apply all the data into calculation ,the data we got show as follow.

Table2 maximum and minimum velocity selected on the graph of run#9

Part 2, read graphs and analyze

Position-times curve

We should put notebook at least 0.40m away from the motion sensor.

We should move the notebook no more than 0.70m.

In order to cover all the slope, we should at least detect the motion until 6th s.

For accuracy consideration, we usually choose the middle part of the slope, while in this graph, the slope was perfectly smooth so we can directly choose the start point (2,0.40) and the end point (6,1.12). So the absolute value of slope (numberically equals average velocity) is

Description of the motion: starting at a position of 0.40m, constant speed of 0.18m/s for 4s followed by no motion for 4s.

velocity-times curve

In this graph, the diatance of this object equals to the area of