iGCSE Physics (0625) 1.1 Physical quantities and measurement techniques-Exam Style Questions- New Syllabus
▶️ Answer/Explanation
Detailed solution:
To find the duration of the third lap, subtract the total time after two laps from the total time after three laps.
The reading after two laps is $02:59$ ($2\text{ min }59\text{ s}$) and after three laps is $04:18$ ($4\text{ min }18\text{ s}$).
Convert the times to seconds: $T_{2} = (2 \times 60) + 59 = 179\text{ s}$ and $T_{3} = (4 \times 60) + 18 = 258\text{ s}$.
The time for the third lap is $\Delta t = T_{3} – T_{2} = 258\text{ s} – 179\text{ s} = 79\text{ s}$.
Converting $79\text{ s}$ back to minutes and seconds gives $1\text{ min }19\text{ s}$.
Thus, the athlete took $1\text{ min }19\text{ s}$ to complete the final lap, which corresponds to Option A.
▶️ Answer/Explanation
Detailed solution:
To find the actual length of the rod, subtract the starting position from the final reading on the ruler.
The rod starts at the $1.0\text{ cm}$ mark and ends at the $5.6\text{ cm}$ mark ($5\text{ cm}$ and $6$ small divisions).
$\text{Length} = \text{Final Reading} – \text{Initial Reading} = 5.6\text{ cm} – 1.0\text{ cm} = 4.6\text{ cm}$.
Since $1\text{ cm} = 10\text{ mm}$, the length in millimeters is $4.6 \times 10 = 46\text{ mm}$.
This method correctly accounts for the “zero error” caused by the damaged end of the ruler.
Therefore, the length of the metal rod is $46\text{ mm}$, which corresponds to option B.
▶️ Answer/Explanation
Detailed solution:
To determine the volume of a liquid like water, a measuring cylinder is the standard laboratory instrument used.
A clock is used for measuring time intervals, while a thermometer measures temperature.
A ruler is typically used for linear measurements of length, though it can find volume for regular solids via V=l×w×h.
Since water is a liquid that takes the shape of its container, it must be poured into a graduated measuring cylinder for an accurate reading.
The scale on the cylinder allows for a direct measurement of the space occupied by the liquid.
Therefore, option B is the correct choice for measuring the volume of water.