The pressure exerted by a phonograph needle on a record is surprisingly large, due to the very small width of the needle. if the equivalent of 1.25 g is supported by a needle, the tip of which is a circle 0.195 mm in radius, what pressure is exerted on the record, in pascals?

102597.6 Pa

Explanation:

mass, m = 1.25 g

Force, F = m x g = 1.25 x 9.8 x 10^-3 = 0.01225 N

radius, r = 0.195 mm = 0.195 x 10^-3 m

Area, A = πr² = 3.14 x 0.195 x 0.195 x 10^-6 m^2

A = 1.19 x 10^-7 m^2

Pressure is defined as the thrust acting per unit area.

P = Force / Area

P = 0.01225 N / (1.10 x 10^-7)

P = 102597.6 Pa

Thus, the pressure exerted is 102597.6 Pa.

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.