a phonograph record 30.0cm in diameter rotates 33.5 times per minute.

What is its frequency?

What is its period?

What is the linear speed of a point on its rim?

What is the centripetal acceleration of a point on its rim?

Respuesta :

The frequency (f) is 33.5 rpm, as given, or 0.59 rev/sec. The period of rotation (T) is 1/f, so 1/0.59 or ~ 1.69 seconds. The linear speed (v) of a point on it's rim is calculated using v= 2*pi*r/T so, v= 2 * pi * (30/2) / 1.69 ==> 2 * 3.14 * 15 / 1.69 ==> 55.74 cm/s. The centripetal acceleration (a) of a point on it's rim is caluclated using a = v^2/r so a = 55.74 ^2 / 15 ==> 207.13 cm/s^2

Explanation:

Given that phonograph rotates 33.5 times per minute:

Frequency of the phonograph = [tex]33.5 min^{-1}[/tex]

Time period =[tex]\frac{1}{frequency}=\frac{1}{33.5 min^{-1}}=0.0298 min[/tex]

time period = 0.0298 × 60 seconds =1.788 seconds

Radius r = 15 cm = 0.15 m (1 m = 100 cm)

The linear speed =[tex]\frac{Distance}{time}=\frac{2\pi\times r}{1.788 sec}=\frac{2\times 3.14\times 0.15 m}{1.788 sec}=0.526 m/s[/tex]

The centripetal acceleration of a point on its rim:

[tex]\frac{(\text{linear velocity})^2}{\text{radius of the rim}}=\frac{(0.526 m/s)^2}{0.15 m}=1.84 m/s^2[/tex]

Centripetal acceleration is [tex]1.84 m/s^2[/tex].