IB Physics HL S1.3.5 Graphing Questions

A group of students is trying to determine the density and the viscosity of a liquid.

To determine the density, they use a balance to read the mass m of a sphere in air and immersed in the liquid.

They use a sphere of volume $V=1.827 \times 10^{-7} \mathrm{~m}^{3}$.
The readings are $m_{\text {air }}=1.427 \mathrm{~g}$ in air and $m_{\text {immersed }}=1.208 \mathrm{~g}$ in the liquid.
The readings are different due to buoyancy. The buoyancy force $F_{\mathrm{b}}$ is given by

where V is the volume of the sphere and $\rho$ is the density of the liquid.

To determine the viscosity, they immerse the sphere in the liquid and drop it from rest.
They collect values and plot a graph of the position d of the sphere from the moment they drop it. They verify that the sphere reaches terminal velocity $v_{t}$ after 0.5 s .

Draw the line of best fit on the graph.