AS Physics paper 3 Question 2

Two readings are not enough to draw a valid conclusion.

Take more readings and plot a graph to confirm the relationship.

Parallax error when measuring [specific length, e.g., the length of a wire / height of a mass].

Use a fiducial marker (like a pointer or pin) or ensure the ruler is clamped right next to the object to read at eye level.

Hard to judge when the [object] reaches the max height / lowest point of its swing.

Use a video camera with a slow-motion playback feature alongside a scale to freeze-frame the exact peak.

Ruler / Newton meter is not perfectly vertical or horizontal (misalignment).

Use a spirit level or plumb line to check and adjust alignment.

The object/string is not perfectly parallel to the scale.

Use a set square against the bench to ensure perpendicular alignment.

Human reaction time causes significant uncertainty when timing [specific event, e.g., a short drop /one oscillation].

Use a video camera with a frame counter/time-stamp to analyze the motion frame-by-frame, OR use light gates connected to a data logger.

Oscillations die out too quickly to time multiple periods.

Use a heavier mass / more aerodynamic shape to reduce air damping, or time fewer oscillations using a video recording.

Hard to judge the exact start/end of an oscillation.

Place a marker at the center of the equilibrium position and start/stop the timer exactly as the object passes it.

Wire / string slips when masses are added or during oscillations.

Secure the wire firmly between two wooden blocks clamped together in a vice.

Mass of the string/spring is not negligible compared to the added masses.

Measure the mass of the string using a digital balance and account for it in calculations.

Diameter of the cylinder/object is not uniform.

Measure the diameter at multiple positions and different orientations using a micrometer screw gauge and calculate an average.

The spring/wire stretches permanently (exceeds elastic limit) during the experiment.

Check the original unloaded length before and after each trial to ensure it returns to its baseline.

Apparatus wobbles / moves on the bench when forces are applied or when oscillating.

Clamp the retort stand securely to the bench using a G-clamp or heavy bench weights.

Friction at the pivot / pulley affects the force readings.

Apply a lubricant (e.g., oil or graphite) to the axle, or use a low-friction ball-bearing pulley.