Question

An electric fan has blades of length 30 cm as measured from the axis of rotation. If the fan is rotating at 1200 rpm, the acceleration of a point on the tip of the blade is about

• A. 1600 $ms^{-2}$
• B. 4740 $ms^{-2}$
• C. 2370 $ms^{-2}$
• D. 5055 $ms^{-2}$

Answer 1

Answer: (B)

4740 $ms^{-2}$

Answer 2

Acceleration of a point at the tip of the blade
= centripetal acceleration
= $\omega^2 R = (2\pi f)^2 R$
= $\left(2 \times \frac{22}{7} \times \frac{1200}{60}\right)^2 \times \frac{30}{100}$
= 4740 $ms^{-2}$