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Ticker Tapes

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A set of slides created to teach Ticker Tapes to students following the South African National Science curriculum (NSC CAPS) in Cape Town.

Text of Ticker Tapes

  • 1. Ticker Tapes BHS Physical Science K Warne

2. Apparatus

  • Trolley & track
  • Inclined plane
  • Ticker timer
  • Ticker tape
  • Power source
  • Compensating for friction
  • Connect up the trolley, tape and ticker timer.
  • Start the timer.
  • Gently push the trolley down the slope.
  • Stop the timer when the trolley hits the end of the track.
  • Examine the ticker tape.
  • Set the angle of the slope so that with agentle pushthe trolley will move down the slope withconstant velocity . (Evenly spaced dots)

3. Constant Velocity

  • Set up apparatus as shown.
  • Compensate for friction
  • Insert a fresh tape, start the timer.
  • Push the trolley slowly down the slope.
  • Repeat steps 3 & 4 but push the trolley faster the second time.

4. Acceleration

  • Set up apparatus as shown.
  • Increase the slope until the trolley ACCELERATES down the slope from a stationary start.
  • Insert a fresh tape, start the timer.
  • Release the trolley from the top of the slope.
  • Repeat steps 3 & 4 but increase the slope the second time so that the trolley accelerates FASTER.

5. Ticker Tape - calculations

  • Analysis of the tapesNote thefrequencyof the timer.
  • Discard the beginning and end of the tapes (unevenly spaced dots).
  • Mark off TWO lengthsorintervals .
  • Anyuneven number of dots (even no. of spaces) will work best.
  • Label these intervalsA - BandC - D
  • The distance between the intervals does not matter but you must be able to see the dots clearly.
  • Measure thedisplacement(distance from first to last dot)across EACH INTERVAL ( S A-B , S C-D ).
  • Find and label theMIDPOINTS(dot 3) of each interval A B & C D x and yrespectively.
  • Count thenumber of spacesbetweenx and y.

... . . ...........SLOWTape moves to LEFTFAST! 6. Ticker Tape - calculations

  • Analysis of the tapes:Note thefrequencyof the timer.
  • Discard the beginning and end of the tapes (unevenly spaced dots).
  • Mark off at least TWO lengthsorintervals . (4 is ideal)
  • Anyuneven number of dots (even no. of spaces) will work best.
  • Label these intervalsA B, B - CandC D ect
  • The number of intervals does not matter but you must be able to see the dots clearly.
  • Measure thedisplacement(distance from first to last dot)across EACH INTERVAL ( S A-B ,S B-C , S C-Dect.)
  • Find and label theMIDPOINTS(dot 3) of each interval A B,B C and C D;w, x, y and zrespectively.
  • Count thenumber of spacesbetween the mid pointsx, y and z

... . . ...........X ABCD S A-B S B-C 12345 Dots W X Time X Y: 1234 Y etc 7. Ticker Tape Calculations Frequency of timer: SPACES/SECPeriod of Timer: SEC/SPACE _______________________ INTERVAL Spaces Time (s) Displacement (m) Average Velocity (m/s) Inst. Velocity at... Change in Velocity Time (s) Acceleration (m.s -2 ) A-B W W X W X W X B-C X C-D Y X Y X Y X Y D-E Z Y Z Y Z Y Z 8. Ticker Tape - calculations If frequency = 50 Hz.:Period = 1/50 = 0.02sTime for Interval (A-B) = spaces x period = 4 x 0.02 = 0.08s Spaces ( X Y): 1234 Frequency of timer: 50 HzPeriod of Timer = 1/FREQUENCY ... . . ...........X X ABCD S A-B S B-C 12345 Dots w x y INTERVAL Spaces Time (s) Displacement (m) Average Velocity (m/s) Inst. Velocity at... Change in Velocity Time (s) Acceleration (m.s -2 ) A-B 4 0.08 0.023 0.023/0.08 0.2875 W W X 0.625 0.2875 =0.3375 W X 0.08 W X 0.3375 0.08 = 4.218 B-C 4 0.08 0.050 0.05/0.08 0.625 X C-D 4 0.08 0.100 0.1/0.08 1.25 Y X Y X Y X Y D-E 4 0.08 Z Y Z Y Z Y Z 9. Ticker Tape - calculations Displacement (S ) = Distance from first dot to last dot. VELOCITY=Displacement(m) time(s) =(m.s -1 ) ACCELERATION=Velocity(m/s) time(s) = v 2- v 1 t 2-1 time= no ofspacesxtimefor eachspace(period)Frequency of timer: ______Period of Timer:_______________________ (m.s -2 ) INTERVAL Spaces Time (s) Displacement (m) Average Velocity (m/s) Inst. Velocity at... Change in Velocity Time (s) Acceleration (m.s -2 ) A-B W W X W X W X B-C X C-D Y X Y X Y X Y D-E Z Y Z Y Z Y Z 10. Ticker Tape Graphs Plot graphs on the ofDISPLACEMENT(m )againstTIME (s)on the same system of axis foreach tapemade.Do the same for andVELOCITY(m/s) againstTIME(s) andACCELERATIONagainstTIME. ... . . ...........X ABCD S x S y w x t 1 t 2 s (m) t (s) t 1 t 2ect S w S x v (m.s -1 ) t (s) t 1 t 2ect v w v y Point Time(s) Disp. (m) Ins.V(m.s -1 ) W X y 11. Ticker Tape

  • INFORMATION KNOWN
  • Foreach intervalyou know the
  • DISTANCE COVERED
  • AVERAGE VELOCITY
  • INSTANTANEOUS VELOCITY (MIDPOINT)
  • TIME TAKEN
  • ACCELERATION

12. Walking Speed Displacement per length CALIBRATION timer frequency = 16 Hz T = 1/f = 1/16 = 0.06 s 0.61.21.82.4 s /(m) t /(s) speed = distance (TOTAL)/time slow fast time 0.60.60.60.6 13. Constant Velocity - calculations t v t s Length Time/(s) Displacement /(m) Velocity I 0 0 0 II 0.6 0.17 0.17 0.6 III 1.2 0.35 0.35-0.17 1.2-0.6 IV 1.8 0.52 0.52-0.35 1.8-1.2 14. Ticker Tape - Graphs t s(m) Displacement vs. time t (s) x x x x v(m/s) t (s) x x x x x Line of best fit X INTERVAL Time/(s) Displacement /(m) Average Velocity /(m/s) Instantaneous Velocity at... A-C 8x( 1 / f ) S A-C S A-C/ time B C-E 8x( 1 / f ) S B-D S B-D/ time C 15. VELOCITY FROM S v T Graph Displacement vs. time AB C DE Tangent (only touches curve at ONE POINT GRADIENT m =Change in Y Change in X (x 1 , y 1 ) (x 2 , y 2 ) Y 2 -y 1 x 2 -x 1 = x 1 y 1 Gradient of the displacement - time graph gives the INSTANTANEOUS VELOCITY at that point. = velocity at......x 2 y 2 2 1 s(m) t (s) x x x x

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