Physical Science K Warne Ticker Tapes Physical Science K Warne

Ticker timer Pracs Compensating for friction Ticker tape Trolley & track Inclined plane Ticker timer Ticker tape Power source trolley 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 a gentle push the trolley will move down the slope with constant velocity. (………..spaced dots)

Constant Velocity Compensate for friction as per previous slide. Set up apparatus as shown. Compensate for friction as per previous slide. Insert a fresh tape, start the timer. Give the trolley a slight push so it moves down the slope with ……………. velocity. Repeat steps 3 & 4 but push the trolley harder the second time.

Acceleration Set up apparatus as shown. Increase the slope until the trolley ………………. 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.

Ticker Tape - calculations ... . . . . . . . . . . . . . SLOW Tape moves to LEFT FAST! Analysis of the tapes Note the frequency of the timer. Discard the beginning and end of the tapes (unevenly spaced dots). Mark off TWO lengths or intervals. Any uneven number of dots (even no. of spaces) will work best. Label these intervals A - B and C - D The distance between the intervals does not matter but you must be able to see the dots clearly. Measure the displacement (distance from first to last dot) across EACH INTERVAL (SA-B, SC-D). Find and label the MIDPOINTS (dot 3) of each interval A – B & C – D – x and y respectively. Count the number of spaces between x and y.

Ticker Tape - calculations SA-B SB-C ... . . . . . . . . . . . . . X X 1 2 3 4 5 Dots A B C D x y w 1 2 3 4 Spaces ( X – Y) Frequency of timer: 50 Hz Period of Timer = 1/FREQUENCY If frequency = 50 Hz .: Period = 1/50 = 0.02s Time for Interval (A-B) = spaces x period = 4 x 0.02 = 0.08s INTERVAL Spaces Time (s) Displacement (m) Average Velocity (m/s) Inst. Velocity at... Change in Velocity Acceleration (m.s-2) A-B W WX … B-C X C-D Y XY D-E Z 0.08 … 0.023/0.08 = 0.2875 … 4 … 0.023 0.050 0.100 … … … … …

Ticker Tape - calculations Frequency of timer: ______ Period of Timer: _______________________ INTERVAL Spaces Time (s) Displacement (m) Average Velocity (m/s) Inst. Velocity at... Change in Velocity Acceleration (m.s-2) A-B W WX B-C X C-D Y XY D-E Z YZ … Displacement (X) = Distance from first dot to last dot. time = no of spaces x time for each space (period) Displacement (m) time (s) VELOCITY = = (m.s-1) Change in Inst. Velocity (m/s) time (s) v2 - v1 t2-1 ACCELERATION = = (m.s-2)

Ticker Tape - calculations Frequency of timer: 50 Hz Period of Timer: 0.02 s per space Constant velocity . . . . . . . . . . . . . . . . . . Displacement (…..) = Distance from first dot to last dot (cm) convert to (m). time = no of spaces x period …………….. (m) time (s) VELOCITY = = (m.s-1) ... . . . . . . . . . . . . . acceleration V2 V1 ……………(m/s) time (s) ……… t2-1 ACCELERATION = = (m.s-2)

Ticker Tape - calculations Frequency of timer: 50 Hz Period of Timer: 0.02 s per space Constant velocity . . . . . . . . . . . . . . . . . . Displacement (X) = Distance from first dot to last dot (cm) convert to (m). time = no of spaces x period Displacement (m) time (s) VELOCITY = = (m.s-1) ... . . . . . . . . . . . . . acceleration V2 V1 Change in Inst. Velocity (m/s) time (s) v2 - v1 t2-1 ACCELERATION = = (m.s-2)

Ticker Tape INFORMATION KNOWN For each interval you know the DISTANCE COVERED AVERAGE VELOCITY INSTANTANEOUS VELOCITY (MIDPOINT) TIME TAKEN ACCELERATIONü

Apparatus (inc diagram) Method Results Prac Write Up: Aim Apparatus (inc diagram) Method Results Calculations (example one fully shown for each type of calculation done) Formula, working and answer eg: Av V = x/ t = 20/0.2 = 100 cm.s-1 Conclusion Analysis