IB Physics HL A 4 8 Hl Rotational Newtons Second Law Questions

Apply rotational Newton’s second law to torque, angular acceleration, rolling, pulley, tension, power and angular-momentum problems.

Exam points

Apply rotational Newton’s second law τ = Iα to relate resultant torque and angular acceleration.
Calculate torque, angular acceleration or moment of inertia in rotating systems using complete mark-scheme evidence.

[Maximum number: 2]

A student models a rotating dancer using a system that consists of a vertical cylinder, a horizontal rod and two spheres.

The cylinder rotates from rest about the central vertical axis. A rod passes through the cylinder with a sphere on each side of the cylinder. Each sphere can move along the rod. Initially the spheres are close to the cylinder.

Figure for Question IB Physics HL A 4 8 Hl Rotational Newtons Second Law Questions question 1 — IB Physics HL

A horizontal force of 50 N is applied perpendicular to the rod at a distance of 0.50 m from the central axis. Another horizontal force of 40 N is applied in the opposite direction at a distance of 0.20 m from the central axis. Air resistance is negligible.

Determine the moment of inertia of the system about the central axis.

$\begin{aligned} I=\frac{\Gamma}{\alpha} \text { OR } 33=I \times 4 I=8.25<\mathrm{kg} \mathrm{~m}^{2}> \end{aligned}$

Allow ECF from (a) and (b)

Award [2] for a BCA

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IB Physics HL A 4 8 Hl Rotational Newtons Second Law Questions question 1