DP Physics (last assessment 2024)

Question 20N.3.HL.TZ0.12c(ii)

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.3.HL.TZ0.12c(ii)
Level	HL	Paper	3	Time zone	TZ0
Command term	Calculate	Question number	c(ii)	Adapted from	N/A

c(ii).

[Maximum mark: 1]

20N.3.HL.TZ0.12c(ii)

A sphere is dropped into a container of oil.
The following data are available.

Density of oil $= 915 kg m^{- 3}$
Viscosity of oil $= 37.9 \times 10^{- 3} Pas$
Volume of sphere $= 7.24 \times 10^{- 6} m^{3}$
Mass of sphere $= 12.6 g$

The sphere is now suspended from a spring so that the sphere is below the surface of the oil.

(c(ii))

The sphere oscillates vertically within the oil at the natural frequency of the sphere-spring system. The energy is reduced in each cycle by $10 %$ . Calculate the $Q$ factor for this system.

[1]

Markscheme

$Q = « 2 π \times \frac{energy stored}{energy lost} = 2 π \times \frac{100}{10} = » 63$ ✓

Examiners report

The calculation needed to obtain the Q-factor proved to be known by many.

Syllabus sections

Option B: Engineering physics

Option B: Engineering physics » Option B: Engineering physics (Additional higher level option topics) » B.4 – Forced vibrations and resonance (HL only)

Option B: Engineering physics » Option B: Engineering physics (Additional higher level option topics)

Question 20N.3.HL.TZ0.12c(ii)

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