PHYS 1420 Lecture Notes - Lecture 26: Net Force, Pressure Measurement, Barometer

• School: York University
• Department: Physics and Astronomy
• Course: PHYS 1420
• Professor: Matthew George

Document Summary

In order to measure what the pressure is of a given fluid is, there are devices which can react in a predictable quantifiable manner to changes in pressure. Fluids: spring-based manometer, f = -kx, p=f/a, p=-kx/a, open-tube manometer, pb = po + pgh. The pressure is the same at the same height: mercury barometer, po=pgh. If the object has the density of (cid:2198)(cid:2197)(cid:2184)(cid:2192)(cid:2187)(cid:2185)(cid:2202), it is also getting pulled downward by gravity which can be written as (cid:2179)=(cid:2198)(cid:2197)(cid:2184)(cid:2192)(cid:2187)(cid:2185)(cid:2202)(cid:2178)(cid:2197)(cid:2184)(cid:2192)(cid:2187)(cid:2185)(cid:2202)(cid:2189: the net force on the object is (cid:2196)(cid:2187)(cid:2202)= (cid:2179)=((cid:2198)(cid:2188)(cid:2203)(cid:2191)(cid:2186) (cid:2198)(cid:2197)(cid:2184)(cid:2192)(cid:2187)(cid:2185)(cid:2202))(cid:2178)(cid:2197)(cid:2184)(cid:2192)(cid:2187)(cid:2185)(cid:2202)(cid:2189, note. If the density of the object is more than the density of the fluid, then the net force is negative and the object sinks. Force: =(cid:2198)(cid:2188)(cid:2203)(cid:2191)(cid:2186)(cid:2204)(cid:2188)(cid:2203)(cid:2191)(cid:2186)(cid:2189, where vfluid is the volume of the displaced fluid, case 1 totally submerged object, objects can only float when the density of the object (p object) is less than the density of the fluid.