| Exam Board | OCR |
|---|---|
| Module | M4 (Mechanics 4) |
| Year | 2005 |
| Session | June |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Moments of inertia |
| Type | Couple applied to rotating body |
| Difficulty | Standard +0.3 This is a straightforward application of rotational kinematics and the rotational equation of motion. Part (i) uses a standard SUVAT-equivalent equation with given values, and part (ii) applies the formula M = Iα directly. While moments of inertia is a Further Maths topic, the question requires only routine substitution into familiar formulas with no conceptual challenges. |
| Spec | 6.05a Angular velocity: definitions |
1 A wheel is rotating freely with angular speed $25 \mathrm { rad } \mathrm { s } ^ { - 1 }$ about a fixed axis through its centre. The moment of inertia of the wheel about the axis is $0.65 \mathrm {~kg} \mathrm {~m} ^ { 2 }$. A couple of constant moment is applied to the wheel, and in the next 5 seconds the wheel rotates through 180 radians.\\
(i) Find the angular acceleration of the wheel.\\
(ii) Find the moment of the couple about the axis.
\hfill \mbox{\textit{OCR M4 2005 Q1 [4]}}