A tiny spherical glass bead is projected vertically downwards into...

The net downward force on the spherical bead is given by $F_{net} = W_{eff} - F_v$, where $W_{eff}$ is the effective weight (weight minus buoyancy)$and F_v$ is the velocity-dependent viscous drag.

At terminal velocity $v_t$, the net force is zero, so $W_{eff} = 6\pi\eta r v_t$.

The bead is projected with an initial velocity $v_0 = 2v_t$. Since $v_0 > v_t$, the initial upward viscous drag is greater than the downward effective weight.

This results in a net upward force, causing the bead to decelerate. As the velocity decreases, the viscous drag decreases, and the net upward force (and thus the retardation) decreases.

The velocity will continuously decrease from $v_0$ and asymptotically approach the terminal velocity $v_t$ from above. The graph is a curve starting at $v_0$ and flattening out to a horizontal asymptote at $v_t$.

Answer: A curve starting at $v_0$ on the velocity axis and decreasing with a continuously flattening slope to approach a horizontal asymptote at $v_t$.