Ping Pong Fun - Video Analysis Project

Transcription

1 Png Pong Fun - Vdeo Analyss Project Objectve In ths experment we are gong to nvestgate the projectle moton of png pong balls usng Verner s Logger Pro Software. Does the object travel n a straght lne? What forces are actng on the ball? What about ar resstance? Does the spn of the ball change ts moton? We wll try to answer these questons by capturng vdeos of png pong balls n flght and dong a curve ft to the data. We wll also explore the horzontal and vertcal components of velocty to help us better understand the equatons. Procedure Step 1 Your group needs to vdeo a pn pong ball n flght. Please be sure to nclude a yard stck somewhere n the vdeo. Ths wll be used to provde us wth a frame of reference for the experment. Be sure the camera s not set up at an angle. Ths wll affect your readngs. Any movement n the camera wll result n naccurate readngs. The ball must stay n the vdeo capture frame of your camera. Step Once the footage has been captured, you can mport the move nto Logger Pro by clckng on Insert Move Browse to \\karentserver\users\physics. Ths s where I stored the vdeos. Step 3 Now that the move s n Logger Pro, you wll begn analyzng the data. Clck on the arrow wth the red dots next to t to along the bottom of the move to expand the data analyss toolbar along the rght hand sde of the vdeo.

2 Step 4 The frst thng you should do s clck on the yard stck con along the rght (the fourth one down) and then hghlght the yard stck n your vdeo. Be as accurate as you can! Note: (1 yard =.9144 m) Then advance the vdeo wth the play button or scroll bar along the bottom to fnd the pont where the ball was just released. Ths wll be the startng pont for the experment. Now clck on the Add Pont tool (the second one down on the rght) and clck rght n the center of your object. If you choose a pont that s not n the mddle t could affect your results (especally f the object spns). When you clck on the object the vdeo wll automatcally advance. Contnue to clck on the object as t travels through the ar untl t hts the ground. Step 5 Now clck on the Set Orgn button (the thrd one down). Set the orgn so that the vertcal axs s algned wth the startng poston of the ball and the x- axs s algned wth the pont of contact at the bottom of ts path. Next you need to do a rght clck on the vdeo and go to Move optons. Be sure under the vdeo analyss secton that Frst VA pont defnes move zero tme. Ths wll help wth you calculatons!!

3 Analyss Step 6 Now t s tme to start analyzng our data. Do a Quadratc Regresson for the Y- axs and a Lnear Regresson for the X-axs.

4 Step 7 Your screen should look smlar to the one below. You may need to adjust the Xmn, Xmax, Ymn and Ymax of your graph to get the best lookng graph. Double clck on the axes to change these values, or smply clck and drag to expand the graph. Step 8 Examne the Quadratc Regresson Equaton: y = At + Bt + C A= B= C= Compare ths formula to our Free Fall Equaton: y = v snθ t 1 gt Usng the tangent feature fnd the slope at the top, mddle and bottom of flght along the y-curve. Top - Mddle - Bottom - What s gravty for your experment? At what ntal heght dd the ball start? What s the ntal velocty n the y-drecton for your experment?

5 The slope of the y-drecton appears to be changng. Compare the slope at the top, mddle and bottom and flght usng the tangent feature n Logger Pro and why you thnk those values make sense. What do you notce about the velocty of the ball as t reaches the top and the sgn of the speed at the begnnng and at the end of flght? Explan why you thnk you got the answers you dd. Step 9 Examne the Lnear Regresson Equaton: x = mt + b m= b= Compare ths formula to our Free Fall Equaton: x = v cosθt Usng the tangent feature fnd the slope at the top, mddle and bottom of flght along the x- curve. Top - Mddle - What s the ntal velocty n the x-drecton accordng to your equaton? Bottom - Accordng to the equaton the slope of the x-drecton curve s a straght lne, whch means that t s constant. Explan why the slope shouldn t change n theory, but why t actually does change for ths experment. You mght want to use the tangent feature to help explan ths. Determne the dstance away the ball landed n the x-drecton by lookng at the graphs or table. If you flmed the vdeo backwards, you wll get a negatve value for x. Ths just means t s movng left.

6 Step 10 - Fnd the overall ntal velocty for the experment: Intal velocty n x-drecton: Intal velocty n x-drecton: Overall ntal velocty: v = v + x v y ( v cosθ ) + ( v snθ ) = v = θ = Extra Credt: On the left hand sde of the graph, select to vew Poston- tme graph and Velocty-tme graph for the Y-drecton:

7 Try to analyze the curves as best you can. Remember the slope of a Poston-tme graph s a velocty and the slope of a Velocty-tme graph s acceleraton (gravty). If you are brave you mght even look at the areas under the curves. The area under a velocty curve wll tell you the dsplacement. Good luck! I look forward to readng some nsghtful dscoveres!!