Question

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 0.200 mm in radius, what pressure is exerted on the record in N/m2?

Answer 1

p=F/A= mg/πr²=
=0.001/3.14•0.0002²=7958 Pa

Answer 2

7937

Answer 3

Elana almost got it right
=0.001/(3.14*(0.0002)^2)=7961.78 or 7962 Pa

Answer 4

pressure is force/Area, in this case, your force is the weight of the needle (remember to take gravity into account) F = .001 * 9.8. Your needle tip has a radius of .002m and the area of a circle is A= pir^2 = 3.14(.002)^2. Your final equation should look like this Pressure = (.001 * 9.8)/(3.14(.002)^2)