waecE-LEARNING
Physics Paper 3, May/June 2014  
Questions: 1 2 3 Main
General Comments
Weakness/Remedies
Strength

 

 

 

 

 

































 

Question 1

(a)

You are provided with a grooved inclined plane, a solid sphere, stop-watch and other necessary materials.

  1. Place the pile of paper towels at the tail end of the inclined plane to stop the sphere from rolling off the table.
  2. Release the sphere from a point at distance D = 1.40 cm from the tail end of the inclined plane.
  3. Determine the average time t taken by the sphere to cover this distance.
  4. Evaluate W =
  5. Calculate V = 2W
  6. Repeat the procedure for four other values of D = 120 cm,100cm, 80 cm and 60 cm respectively.
  7. Tabulate your readings.
  8. Plot a graph with V on the vertical axis and t on the horizontal axis.
  9. Determine the slope s of the graph.
  10. What is the significance of s?
  11. State two precautions taken to obtain accurate results.

 

(b)       (i)         Write the equation for the velocity ratio of an inclined plane, giving the meanings of the symbols used.
            (ii)        An object of mass 5 kg is placed on a plane inclined as an angle of 30o to the horizontal.  Calculate the force on the object perpendicular to the plane when the object is at rest [g = 10 ms2]

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Observation

Part (b) was poorly answered.  Many candidates could not write the correct formula to evaluate the force.  Most wrote mgSinӨ.  Those that got the correct formula substituted wrongly.

Candidates were expected to:

-     record five values of d  to at least 1 d.p. in cm                                                                                                                                                          
-     read and record five values of t  to at least 1 d.p  in second and in trend 
-     read and record five values of t2 to at least 1 d.p. in seconds and in trend
-     correctly evaluate five values of tave
-     read and record five values of  W =  to at least 2 d.p.
-     correctly calculate five values of V = 2W
-     show composite table containing d, t, w and V
-     plot graph using reasonable scales
-     draw line of best fit
-     determine the slope of the graph
-     state the significance of the slope as the acceleration of the rolling object
-     state any two of the following precautions.

e.g.

-     ensured inclined plane is firmly clamped/inclination of the plane is constant
-     avoided parallax error in reading stop watch/metre rule
-     noted and corrected / avoided zero error on stop watch/metre rule

In part b, the expected answers are:
                    (b)    (i)      V.R  =           

                                     Where    is the angle of inclination                                                                                                                                              
                                                                                          
                                                 OR
                                      V.R   =            

Where l  is the distance moved by effort / length of inclined plane and h is the distance moved by load / length of inclined plane                                                                                              
                                    (Accept labelled diagram)
                                     (ii)     Force perpendicular to the plane

                                                =  mgcos  
                                                =  5 x 10 x cos 30
                                                =  43.3N


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