Force and Motion I: Paper 3 Guide (Form 4 SPM Physics)

Paper 3 at a glance

• Paper 3 carries 15 marks

Experiment: Determining gravitational acceleration g by free fall

To determine the value of gravitational acceleration g by timing a steel ball falling freely through measured heights.

• Manipulated: Height of fall, h
• Responding: Time of fall, t
• Constant: The same steel ball and release mechanism
• Graph: Plot h (y-axis) against t² (x-axis). A straight line through the origin shows h is directly proportional to t².
• Analysis: For free fall from rest, h = ½gt², so the gradient of the h–t² graph equals ½g. Therefore g = 2 × gradient.

• Full experiment page

Experiment: Relationship between inertia and mass using an inertial balance

To investigate how the inertia of an object, shown by its period of oscillation on an inertial balance, depends on its mass.

• Manipulated: Mass loaded on the inertial balance, m
• Responding: Period of horizontal oscillation, T
• Constant: The inertial balance (its stiffness) and the amplitude of oscillation
• Graph: Plot T² (y-axis) against m (x-axis). The straight line shows that a larger mass gives a longer period, and T² is directly proportional to m.
• Analysis: A greater mass has greater inertia, so it resists the change in its motion more and takes longer to complete each oscillation. The period T (and T²) therefore increases as the mass increases.

• Full experiment page

Paper 3 skill checklist

• Table: quantities with units in the headings, consistent decimal places, derived column calculated correctly.
• Graph: axes labelled with unit, scale using more than half the grid, points plotted with a sharp pencil, best-fit line.
• Gradient: a large triangle on the line, coordinates shown, unit of the gradient stated.
• Relationship: "y increases linearly with x" or "y is directly proportional to x" only if the line passes through the origin.
• Precaution: one that improves accuracy, stated with its reason.

More on graph skills

• Graph skills hub
• All Paper 3 experiments

More Force and Motion I resources

• Chapter overview: Force and Motion I
• Revision Notes
• Common Mistakes
• Practice Questions
• Paper 2 Answering Guide
• Key Terms
• Calculation practice sets

Source: DSKP KSSM Physics Form 4 and 5 (Versi English), Sijil Pelajaran Malaysia: Format Pentaksiran mulai 2021, Fizik (4531) (Bahagian Pembangunan Kurikulum (BPK), KPM)