Physics Paper 3 WASSCE (PC), 2022

Question 1

 

A wooden block of mass, m = 100g, was placed on a rough wooden surface board of length 70 cm, as shown in Fig. 1(a)(i) above.

The wooden block was placed at a distance, x, from the end of the rough wooden surface and the board was raised until it attained a vertical height, h, where the wooden block was just about to slide down the surface of the wooden as shown in Fig. 1(a)(ii) above.

The procedure was repeated for four other values of xi and the corresponding vertical height, hi, was read where i = 1,2,3,4, and 5 respectively.

Fig 1(b) below shows the various values of xi while Fig. 1(c) shows the corresponding values of hi.

Using the diagram as a guide, carry out the following instructions.

(i)         Read and record the values of xiand hiin Fig. 1(b) and Fig. 1(c)  and in each case convert xito real values of Xi and hito real values, Hi, using the scales provided,
where i = 1,2,3,4, and 5 respectively.
(ii)        Evaluate in each case Xi-1 and Hi-1.
(iii)       Tabulate your results.
(iv)       Plot a graph of H-1on the vertical axis and X-1 on the horizontal axis starting both axes from the origin (0,0).
(v)        Determine the slope, s, of the graph.
(vi)       Evaluate k =

(vii)      State any two precautions you would have taken if you were to perform the experiment above.
(b)       (i)         Define friction.

(ii)        State two methods of reducing the effect of friction.


Observation

 

    1. Five values of xiraw correctly measured and recorded to at least1 d.p and within toleranceof± 0.1cm
    2. Five values of Xicorrectlyconverted           
    3. Five values of hiraw correctly measured and recorded to at least1 d.p and within toleranceof± 0.1cm
    4. Five values of Hicorrectlyconverted.
    5. Five values of Xi-1  correctly evaluated to at least3d.p     
    6. Five values of Hi-1  correctly evaluated to at least3d.p    
    7. Composite table showing at least x, h, X, H, X-1and H-1.

TABLE OF RESULTS
                       


Xi Raw ± 0.1 cm

Conv. Xi

hi Raw ± 0.1 cm

Conv. Hi

Xi-1

Hi-1

1.0

10

1.9

5.7

0.100

0.175

2.0

20

3.8

11.4

0.050

0.088

3.0

30

5.8

17.4

0.033

0.057

4.0

40

7.7

23.1

0.025

0.043

5.0

50

9.8

29.4

0.020

0.034

GRAPH

  1. Both axes correctly distinguished
  2. Reasonable scales
  3. Five points correctlyplotted
  4. Line ofbestfit

 

Precautions

  1. Avoid/Avoided parallax error when taking metrerulemeasurements.
  2. Note/Noted/correct/corrected zero error on metrerule.
  3. Ensure/Ensured the board was gently raised.
  4. Ensure/ensured that the tube does not touch the vessel.
  5. Repeated readings (stated).

 

(b)  (i)       Friction.
Friction is the force that opposes motion between two surfaces in contact.

 

 Methods of Reducing Friction

    1. Polishing/smoothing the surfaces incontact.
    2. Lubrication.
    3. Using ballbearings.
    4. Streamlining.
    5. Reduce pressure/weight on the object.
    6. Reduce contact between surfaces by electrostatic and magnetic levitation