KVPY SX SB Exam 2013 Question Paper

Question : 37 of 120

Marks: +1, -0

A plank is resting on a horizontal ground in the northern hemisphere of the Earth at a 45° latitude. Let the angular speed of the Earth be ω and its radius

r_e

. The magnitude of the frictional force on the plank will be

$mr_eω^2$
${mr_eω^2}/√2$
${mr_eω^2}/2$
zero

Validate

Solution:

\F_\r = \m\ω^2 \r \cos 45°

where r = Rcos 45°

\F_\r={\m\ω^2\R}/2

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