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Mechanics · Part 3 of 4
6 exam-style questions with model answers, plus 6 quick multi-choice questions — every question on this part of the standard, grouped by the 2 pages of notes they come from.
Write a full answer before you reveal the model one. That comparison is where the learning happens.
A disc spins at a constant rad s−1.
Show that a point on the rim, m from the axis, moves at m s−1.
A turntable slows from rad s−1 to rest in s at constant angular acceleration.
Calculate the angle it turns through while stopping.
A wheel of radius m accelerates uniformly from rest to rad s−1 in s.
Determine the tangential and centripetal accelerations of a point on the rim at the final instant, and explain why they point in different directions.
A flywheel of rotational inertia kg m2 experiences a net torque of N m.
Show that its angular acceleration is rad s−2.
A disc of rotational inertia kg m2 spins at rad s−1.
Calculate its rotational kinetic energy and its angular momentum.
A student stands on a freely rotating stool holding masses out at arm's length, turning at rad s−1 with rotational inertia kg m2. They pull the masses in, reducing the inertia to kg m2.
Determine the new angular velocity, and explain what happens to the rotational kinetic energy and where any change comes from.