IB Physics SL A.1.9 Fluid resistance on projectiles Question Bank

Practise IB Physics SL A.1.9 by explaining how fluid resistance changes speed and acceleration during a fall or projectile motion.

Exam points

Describe how resistive force changes as an object speeds up through a fluid.
Explain why acceleration decreases toward zero as terminal speed is approached.
Interpret velocity, acceleration or displacement graphs when air resistance is not negligible.

[Maximum number: 3]

This question is about kinematics.

After the stone in (a) hits the water surface it rapidly reaches a terminal speed as it falls through the water. The stone leaves Fiona's hand at time t=0. It hits the water surface at $t_{1}$ and it comes to rest at the bottom of the water at $t_{2}$ . Using the axes below, sketch a graph to show how the speed v of the stone varies from time t=0 to just before $t=t_{2}$ . (There is no need to add any values to the axes.)

Figure for Question A.1.9—Fluid resistance on projectiles question 1 — IB Physics SL

Figure for Answer to Question A.1.9—Fluid resistance on projectiles question 1 — IB Physics SL

straight line to water surface;
clear decrease after hitting surface;
constant non-zero speed reached smaller than maximum; $; \begin{aligned} & \text { (speed must be less than } \\ & \text { maximum velocity) }\end{aligned}$

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A.1.9—Fluid resistance on projectiles question 1