4. (a) Which of these is a vector quantity? A mass B force C energy D distance (b) Figure 7 shows a ball bearing as it falls slowly through a clear, dense liquid - Edexcel - GCSE Physics Combined Science - Question 4 - 2021 - Paper 1

To determine the average speed of the ball bearing falling through the liquid, follow these steps:

1. Apparatus: Use a ruler (or measuring tape) to measure the distances, a stopwatch to measure the time, and a transparent container filled with the dense liquid.

2. Measurement of Distance: Mark a specific distance (e.g., 10 cm) from the top and bottom of the liquid in the container.

3. Measurement of Time: Release the ball bearing from the top mark and use the stopwatch to measure the time it takes to reach the bottom mark.

4. Calculation of Speed: Use the formula for speed:

   $\text{speed} = \frac{\text{distance}}{\text{time}}$

   Calculate the speed by dividing the measured distance by the recorded time.

To ensure accuracy in measuring the speed of the ball bearing, you can:

1. Add More Lines (at Equal Distances): Draw additional lines in the liquid at equal intervals (e.g., every 5 cm). This will provide multiple measurements.
2. Measure the Time of Fall for Each Distance: Use the stopwatch to measure how long it takes for the ball bearing to fall from the top to each marked line.
3. Compare the Times: After collecting the times for each segment, compare them to determine consistency and calculate the average speed for more reliable results.