The blade of an electric shaver vibrates in a simple harmonic motion with a frequency 235.0 Hz over a distance 6.6 mm. What is the amplitude of vibration?

3.3 mm

Explanation:

The electric shaver is vibrating back and forward covering a distance of 2 mm, therefore, the amplitude of this vibration is always the half of the distance.

So the expression to use is:

A = D/2

A = 6.6 / 2 = 3.3 mm

Now, suppose you want the speed of this vibration:

V = 2πfA

V = 2π * 235 * 0.0033

V = 4.87 m/s