Mathematics and Society - OS X Lion Server

PRE.5'2>URE: I~ GIVE./-.l l"l 'ORee: (POUtJDS)PER SQUARe:: UI\.)IT.WHICHEXERT5 MORE. PRESSURE:?It makes sense that anelephant exerts a lot ofpressure on the ground, butwhat about the needle of aphonograph?THE £,U:'PHAl\lT OR THE PHOl\lOGRA,PH t-JE:E:OU::'?1) The oval point of a phonograph needle fits into a .0002-inch by .0007­inch rectangle. The force of the needle on the record is .0033 pounds.(If .0033 pounds of force would be on every .0002-inch by .0007-inchrectangle, how many pounds of force would be on one square inch?2) A large elephant weighs about 10,000 pounds. Suppose an elephantthat weighs 10,000 pounds stood on one of his legs. Suppose the foothe is standing on covers one square foot. How many pounds of forcewould be on one square inch?3) Which exexts more pressure (force per square inch), an elephant or aphonograph needle?4) The information given in problem 1 was for a high quality needle(stylus) and turntable. Do you see why some heavy arms on phonographscould ruin records after several plays? (268