PHYSICS 111 Pressure and Fluids Practice Problem 1

PHYSICS 111 Pressure and Fluids

Practice Problem 1 A gas sample is confined in a chamber with a piston. A small load is put on the piston. If the total weight of piston and load is 36 N and the piston has an area of 2*10^-3 m^2, what is the pressure exerted on the piston by the gas? � Note: atm = 1. 013 * 10 ^5 �

Solution: � � � P = W total / A + atm = 36 / 2*10^-3 + 1. 103*10^5 = 128300 or 1. 3 * 10 ^5 Pa

Practice Problem 2: � A column of water of height 60 cm supports a column of an unknown liquid that is 24 cm height. The density of water is 1 * 10 ^3 kg/m^3. Determine the density of the unknown liquid

Solution: � � � P water = p unknown Mass density * g * h + atm = Mass density * g * h + atm Atm and gravity are same for both and cancell Mass density * h = mass density * h 1 * 10 ^3 * 60 = 24 * mass density Mass density of unknown = 2500 0 r 2. 5 *10 ^3 kg/m^3

Practice Problem 3: � A barber raises his customer’s chair by applying a force of 150 N to a hydraulic piston of area 0. 01 m 2. If the chair is attached to a piston of area 0. 1 m 2, how massive a customer can the chair raise? Assume the chair itself has a mass of 5 kg.

Solution: � To solve this problem, first determine the force applied to the larger piston. �F 2 = F 1 ( A 2 / A 1) Pascal's principle � 150 (. 10 /. 01) = 1500 N �F=ma � 1500/9. 81 = m = 153 kg -5 kg for chair = 148 kg

Practice Problem 4: � A ball of mass 2 kg having diameter of 50 cm falls in the swimming pool. Calculate its buoyant force and volume of water displaced.

Solution: � � � Given: Mass of water, m = 2 kg, Diameter of ball, d = 0. 5 m r = 0. 25 m Volume of sphere = 4/3 pie r^3 =. 0208 m^3 Density= mass /volume = 2 /. 0208 = 96 kg/m^3 F=mg = 2*9. 81 = 19. 6 N Archimedes formula = F= mass density *g*v displaced � V displaced = F/ pg = 19. 6 / 96 *9. 81 =. 0208 m^3