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Question 22M.2.SL.TZ2.b.i

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Date May 2022 Marks available [Maximum mark: 2] Reference code 22M.2.SL.TZ2.b.i
Level SL Paper 2 Time zone TZ2
Command term Show that Question number b.i Adapted from N/A
b.i.
[Maximum mark: 2]
22M.2.SL.TZ2.b.i

Airboats are used for transport across a river. To move the boat forward, air is propelled from the back of the boat by a fan blade.

An airboat has a fan blade of radius 1.8 m. This fan can propel air with a maximum speed relative to the boat of 20 m s−1. The density of air is 1.2 kg m−3.

In a test the airboat is tied to the river bank with a rope normal to the bank. The fan propels the air at its maximum speed. There is no wind.

Show that a mass of about 240 kg of air moves through the fan every second.

[2]

Markscheme

πR2 OR «mass of air through system per unit time =» Avρ seen ✓

244 «kg s−1» ✓

 

Accept use of Energy of air per second = 0.5 ρΑv3 = 0.5 mv2 for MP1.

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