Physics Paper 1, MAy/June. 2011  
Questions: 1 2 3 4 5 6 Main
General Comments

















Alternative b
Question 4

(a)  Diagram

      You are provided with two retort stands, two metre rules, pieces of thread and other
      necessary apparatus.

  1. Set-up the apparatus as illustrated above ensuring that  the strings are permanently 10 cm from either end of the rule.
  2. Measure and record the length L = 80 cm of the two strings.
  3. Hold both ends of the rule and displace the rule slightly, then release so that it oscillates about a vertical axis through its centre.
  4. Determine and record the time t for 10 complete oscillations.
  5. Determine the period T of oscillations
  6. Evaluate log T and log L,
  7. Repeat the procedure for four other values of L = 70, 60, 50 and 40 cm.
  8. Tabulate your readings.
  9. Plot a graph with log T on the vertical axis and log L on the horizontal axis.
  10. Determine the slope, s, and the intercept, c on the vertical axis.
  11. State two precautions taken to ensure accurateresults.      
    b (i)   Define simple harmonic motion
    (ii)    Determine the value of L corresponding to  t = 12s from the graph in (a) above. 

The observation and its tabulation were well handled by most responding candidates.  However, the evaluation of Log L and Log T to the nearest decimal places was poorly tackled.

The plotting of the graph of log T against Log L was poorly handled.  Evaluation of slope and determination of intercept on the vertical axis was fairly attempted.  Candidates were able to state the precautions correctly in acceptable language.

The part b was fairly handled by most responding candidates as they were able to define simple harmonic motion but could not satisfactorily deduce the value of L from the graph when t = 12s probably because of  the Logarithm involved.

In part (a) candidates are expected to:

-    Measure and record five values of L to at least 1 d.p. and in trend.
      Trend: As L increases, t, decreases
-    Evaluate five values each of T, log L and log I to at least 3 s.f.
-    Record data in composite table
-    Plot five point, correctly using reasonable scales and distinguished axes
-    Draw line of best fit.
-    Determine the intercept on the vertical axes and the slope of the graph using large
      right-angled triangle.

 State any two of the following precautions in acceptable language.

 -     Ensured supports of pendula were rigged
 -     Avoided parallax error on meter rule/stop watch
 -     Zero error was noted and corrected on metre rule/stop watch/clock
 -     Ensured smooth and regular oscillations in a horizontal plane
 -     repeated readings shown on table

Part b expected answer are:

  1.   Simple harmonic motion is the motion of a body whose acceleration is always directed towards a fixed point and is proportional to the displacement from the fixed point.
  2.   T   =      =   1.2 secs
    Log 1.2  =  0.079
      0.079 shown on graph with corresponding log L read
      L correctly determined.

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