The pressure exerted by a phonograph needle on a record is surprisingly large, due to the very small width of the needle. show answer Incorrect Answer If the equivalent of 0.95 g is supported by a needle, the tip of which is a circle 0.205 mm in radius, what pressure is exerted on the record, in pascals

Explanation:

Given that,

Mass support is

M = 0.95g= 0.95/1000 = 0.00095kg

Radius of circle R = 0.205mm

r = 0.205/1000 = 0.000205m

Then, area of the circle can be determined using

A = πr²

A = π × 0.000205²

A = 1.32 × 10^-7 m²

From pressure definitions

Pressure = Force / Area

The force is perpendicular to the area

Force = weight = mg

F = mg = 0.00095 × 9.8

F = 9.31 × 10^-3 N

Then,

Pressure = Force / Area

P = F/A

P = 9.31 × 10^-3 / 1.32 × 10^-7

P = 70,530.30 N/m²

Since 1 pascal = 1 N/m²

Then,

P = 70,530.30 Pascals

this would be about 43%