DP Physics (last assessment 2024)

Question 20N.2.SL.TZ0.b

Date	November 2020	Marks available	[Maximum mark: 2]	Reference code	20N.2.SL.TZ0.b
Level	SL	Paper	2	Time zone	TZ0
Command term	Show that	Question number	b	Adapted from	N/A

[Maximum mark: 2]

20N.2.SL.TZ0.b

The Rotor is an amusement park ride that can be modelled as a vertical cylinder of inner radius $R$ rotating about its axis. When the cylinder rotates sufficiently fast, the floor drops out and the passengers stay motionless against the inner surface of the cylinder. The diagram shows a person taking the Rotor ride. The floor of the Rotor has been lowered away from the person.

The person must not slide down the wall. Show that the minimum angular velocity $ω$ of the cylinder for this situation is

$ω = \sqrt{\frac{g}{μ R}}$

where $μ$ is the coefficient of static friction between the person and the cylinder.

[2]

Markscheme

See $F = μ N$ AND $N = m R ω^{2}$ ✓

«substituting for N» $μ m ω^{2} R = m g$ ✓

Syllabus sections

Core

Core » Topic 6: Circular motion and gravitation » 6.1 – Circular motion

Core » Topic 2: Mechanics » 2.2 – Forces

Core » Topic 2: Mechanics

Core » Topic 6: Circular motion and gravitation

Question 20N.2.SL.TZ0.b

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