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JAMB Physics 2019 Paper

Question : 78

Total: 100

Solution:

Concept:

The tip of the seconds hand moves in uniform circular motion, so its linear speed equals the product of angular speed and radius.

Explanation:

The seconds hand completes one full revolution,

\theta = 2\pi

rad, in

60

Therefore, angular speed:

\omega = \dfrac{\theta}{t} = \dfrac{2\pi}{60} = \dfrac{\pi}{30}

rad/s.

The radius equals the length of the hand:

r = 0.1

Linear speed:

v = \omega r = \dfrac{\pi}{30} \times 0.1 = \dfrac{\pi}{300}

m/s.

Using

\pi = 3.142

v = \dfrac{3.142}{300} = 0.01047

m/s.

v \approx 1.05 \times 10^{-2}

m/s.

Answer:

Option A:

1.05 \times 10^{-2}

m/s.

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