Physics 5054 · O Level · Physical quantities and measurement techniques

Physical quantities and measurement techniques — practice question

The maker of 'Super Quilted Paper Towels' says that these white paper towels are more absorbent than another brand of yellow towels. A student plans an experiment to test the absorbency of paper towels. The student pours $30\,\text{cm}^3$ of water into a small shallow dish. He then cuts one paper towel into sixteen identical small squares. One small square is put into the water and then lifted out using tongs, as shown in Fig. 2.1. The student holds the wet square above the water and gently shakes it twice before placing it in a beaker. He carries on with more squares until all of the water has been taken out of the shallow dish. He records the number of squares needed to remove all of the water from the shallow dish.
(a(i))[1]

Suggest why the student shakes each square of towel before putting it into the beaker.

(a(ii))[1]

Explain why the student cuts the towel into small squares instead of using one whole towel.

(a(iii))[1]

Suggest why the student does not cut the towel into very small squares.

(b(i))[4]

On Fig. 2.3, draw the graph of $N$ on the $y$-axis against $V\,/\,\text{cm}^3$ on the $x$-axis. Begin both axes at the origin. Add the straight line of best fit.

(b(ii))[1]

Determine the gradient of your line. Show how you worked it out.

(b(iii))[1]

Suggest why the student decides to repeat the reading for $V = 25\,\text{cm}^3$.

(b(iv))[1]

The paper towel was divided into 16 identical small squares. Use your graph to find the volume of water that a whole paper towel can absorb.

(c)[1]

The student repeats the experiment with the other brand of yellow towels. The graph of $N$ against $V\,/\,\text{cm}^3$ for the yellow towels is steeper than the graph for white towels. State and explain whether the white or yellow paper towels are more absorbent.

(d)[1]

The yellow paper towels are smaller than the white paper towels. Explain whether the student should choose either: A to cut each yellow towel into 16 small squares, or B to cut the yellow towel into squares with the same size as the white-towel squares.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Get rid of extra water / shake off drops / prevent spilling / remove surface water / repeat this each time” …

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI