The pressure exerted by a phonograph needle on a record is surprisingly large. if the equivalent of 1.00 g is supported by a needle, the tip of which is a circle 0.210 mm in radius, what pressure is exerted on the record in n/m2?

Pressure, P = Force, F/ Surface Area, A

In the current scenario,
Force, F = Weight = mg = 1/1000*9.81 = 9.81*10^-3 N
Surface area, A = πr^2 = π*(0.210/1000)^2 = 1.385*10^-7 m^2

Therefore,
P = F/A = (9.81*10^-3)/(1.385*10^-7) = 70,807.71 N/m^2

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