AP Physics C: Mechanics 5.2: Linear & Rotational Motion

Practise AP Physics C: Mechanics 5.2 by linking linear distance, speed and tangential acceleration to angular quantities for rigid bodies, gears and rotating boards.

Exam points

Use gear tooth counts to determine the angular-speed ratio of two meshed gears.
Calculate a rotating point’s tangential acceleration from radius and angular acceleration using aₜ = rα.

Covered syllabus points

5.2.A—Describe the linear motion of a point on a rotating rigid system that corresponds to the rotational motion of…

[Maximum number: 2]

Figure for Question 5.2 Connecting Linear and Rotational Motion question 1 — AP Physics C: Mechanics

Mech. 3. A uniform, rigid, thin board that is 2.4 m long and weighs 200 N is attached to a post by a pivot at point P and hangs over the edge of a building, as shown above. A crate weighing 400 N is attached to the right end of the board. The left end of the board, 0.80 m from the pivot, is attached to a light vertical wire anchored at the other end to keep the board from rotating.

(d) Suppose that the wire breaks and the board begins to pivot about point P. Calculate each of the following.

ii. The magnitude of the initial linear acceleration of the left end of the board

ii. 2 points For a correct relationship between angular and linear acceleration $a=r \alpha$ $a=(0.80 \mathrm{~m})\left(6.13 \mathrm{rad} / \mathrm{s}^{2}\right)$ For an answer consistent with part (d)i. $a=4.9 \mathrm{~m} / \mathrm{s}^{2} \quad\left(\right.$ or $5.0 \mathrm{~m} / \mathrm{s}^{2}$ using $\left.g=10 \mathrm{~m} / \mathrm{s}^{2}\right)$

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Covered syllabus points

5.2 Connecting Linear and Rotational Motion question 1