IB Physics SL A.1.5 Instantaneous and average values Question Bank

Practise IB Physics SL A.1.5 by distinguishing average and instantaneous speed or velocity and reading their values from motion data.

Exam points

Calculate average speed or velocity from total distance, displacement and elapsed time.
Use a graph or tangent to estimate instantaneous speed or velocity at a stated time.
Explain why average speed and average velocity can differ when direction changes.

[Maximum number: 3]

This question is in two parts. Part 1 is about kinematics and gravitation. Part 2 is about radioactivity.
Part 1 Kinematics and gravitation
A ball is released near the surface of the Moon at time t=0. The point of release is on a straight line between the centre of Earth and the centre of the Moon. The graph below shows the variation with time t of the displacement s of the ball from the point of release.

Figure for Question A.1.5—Instantaneous and average values question 1 — IB Physics SL

Use the graph to

estimate the velocity of the ball at $t=0.80 \mathrm{~s}$ .

tangent drawn to curve at 0.80 s ;
correct calculation of gradient of tangent drawn;
$-1.3 \pm 0.1 \mathrm{~m} \mathrm{~s}^{-1}$ or $1.3 \pm 0.1 \mathrm{~m} \mathrm{~s}^{-1}$ downwards;
or
correct coordinates used from the graph; substitution into a correct equation;
$-1.3 \pm 0.1 \mathrm{~m} \mathrm{~s}^{-1}$ or $1.3 \pm 0.1 \mathrm{~m} \mathrm{~s}^{-1}$ downwards;

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A.1.5—Instantaneous and average values question 1