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JAMB Physics 2021 Paper

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Question : 20

Total: 40

Particles of mass 10

^{-2}

kg is fixed to the tip of a fan blade which rotates with angular velocity of 100rad

^{-1}

. If the radius of the blade is 0.2m, the centripetal force is?

2N
20N
200N
400N

Solution:

Concept:

Centripetal force is given by

F = m\omega^2 r

, where

m

is mass,

\omega

is angular velocity, and

r

is radius.

Explanation:

Given:

m = 10^{-2}\ \mathrm{kg}

,

\omega = 100\ \mathrm{rad\,s^{-1}}

, and

r = 0.2\ \mathrm{m}

.

Substitute into the formula:

F = m\omega^2 r = 10^{-2} \times (100)^2 \times 0.2

F = 0.01 \times 10000 \times 0.2

F = 20\ \mathrm{N}

Answer:

The centripetal force is

20\ \mathrm{N}

, which is option B.

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