IB Physics SL A 2 10 Viscous Drag Questions

Practise IB Physics SL A.2.10 by explaining viscous drag, terminal speed and the balance of vertical forces in a fluid.

Exam points

Apply Stokes’ law for viscous drag on a small sphere, Fd = 6πηrv, with drag opposite the motion.
Relate viscosity, sphere radius and speed to drag or terminal motion using complete mark-scheme evidence and correct units.

[Maximum number: 4]

A spherical oil droplet is released from rest at the bottom of a column of water.

The graph shows the variation with time t of the vertical velocity of the oil droplet.

Figure for Question IB Physics SL A 2 10 Viscous Drag Questions question 1 — IB Physics SL

(a)

Describe why the acceleration of the oil droplet changes.

[ 2 ]

(b)

Explain why the velocity of the oil droplet is constant for $t>3 \mathrm{~s}$ .

[ 2 ]

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IB Physics SL A 2 10 Viscous Drag Questions question 1

Question (a)

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