Atmospheric Pressure and Pressure in Liquids – 15.7P, 15.8P, 15.9P, 15.10P, 15.12P, 15.13P, 15.14P, 15.15P, 15.16P, 15.17P

About the lecture

In this mini-lecture, we cover Topics 15.7P, 15.8P, 15.9P, 15.10P, 15.12P, 15.13P, 15.14P, 15.15P, 15.16P, and 15.17P with a discussion of atmospheric pressure and pressure in liquids. In particular, we consider: (i) atmospheric pressure, which is the the pressure of the gas surrounding us on Earth, and where it comes from; (ii) the standard value of atmospheric pressure: 101,325 Pascals (Pa); (iii) the Magdeburg hemisphere experiment that demonstrates the power of atmospheric pressure; (iv) the pressure at the bottom of a column of liquid; (v) the total weight of a liquid, W = Vρg, from which we combine with P = F/A to get that P = hρg, where P is the pressure, h is the height of the column of liquid, ρ is the density of the liquid, and g is the acceleration due to gravity; (vi) the forces acting on a liquid: atmospheric pressure, horizontal and vertical forces due to pressure in the liquid, and the weight of the liquid itself; (vii) up-thrust and it’s affect when an object with the same density as the liquid, a higher density than the liquid, and a lower density then the liquid is inserted into the liquid; (viii) the wight of the displaced liquid, which is equal to the up-thrust force that the object experiences; (ix) three ways to control the weight of displaced liquid to increase the up-thrust force: increase the volume of the displaced liquid, increase the density of the liquid, or increase acceleration due to gravity; and (x) how a boat floats.

About the lecturer

Chris Bell is a Senior Lecturer in the School of Physics at the University of Bristol. His research focuses on the creation and control of novel electronic phases of matter in metals, semiconductors, and insulators. Recently his work has centred on low dimensional systems, including low-density high-mobility two-dimensional superconductors as well as ultrathin ferromagnets.