QCAA Physics Alternative Sequence Linear motion and force

Acceleration due to gravity is independent of an object's mass, so using a lighter or heavier object will not affect the experimental value or its percentage error.

While conducting more trials reduces random error and improves the reliability of the average result, it does not decrease the percentage error inherent in the individual measurements themselves.

Increasing the drop height increases the total time of the fall. Since the absolute uncertainty in timing (like human reaction time) remains relatively constant, a larger measured time results in a significantly smaller percentage error.

Although a stopwatch is more precise than counting, human reaction time (typically around $0.2\text{ s}$) still introduces a massive percentage error for a short drop from eye-level (which takes only about $0.5\text{ s}$).

This is incorrect. This value might result from an algebraic error when solving the conservation of momentum equation, such as solving for $2v$ instead of $3v$.

Correct. Using conservation of momentum, $m(v + 40) + mv = 2m(3v)$, which simplifies to $2v + 40 = 6v$. Solving for $v$ gives $10 \text{ m s}^{-1}$, making the final velocity $3v = 30 \text{ m s}^{-1}$.

This is incorrect. This value represents the difference in initial velocities between object X and object Y, not the final velocity of the combined object Z.

This is incorrect. This value represents the initial velocity of object X ($10 \text{ m s}^{-1} + 40 \text{ m s}^{-1}$), rather than the final velocity of object Z.