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
