Paper 3 · June 2023 · Kinematics and Dynamics
A student repeats a measurement many times using an instrument that has not been checked for a zero error. Which statement correctly describes how random and systematic errors affect the set of readings obtained?
ARandom errors scatter the readings on either side of the true value and are reduced by averaging, while a systematic error shifts every reading the same way and is not.
BRandom errors shift every reading by the same amount in the same direction, while a systematic error scatters the readings on either side of the true value.
CRandom errors and systematic errors both scatter the readings on either side of the true value, and averaging enough readings removes each of them.
DRandom errors affect only the last digit of a reading, while a systematic error changes the size of the physical quantity that is being measured.
Explanation
A random error arises from unpredictable variation in the measurement, so successive readings fall above and below the true value; taking a mean of many readings cancels much of it and improves precision. A systematic error, such as an uncorrected zero error, displaces every reading by the same amount in the same direction, so averaging repeats it rather than removing it, and the result is inaccurate however precise it looks.
Derived from ZIMSEC Physics Paper 3, June 2023, Q1