#### Hydraulics and Pneumatics

A 23.3-kg ladder has a length of 7.50 m. With the bottom of the ladder on horizontal ground, it leans up against the vertical wall of a house; its point of contact with the house is 7.09 m above the ground. If the point of contact with the house is friction less but the point of contact with the ground is not friction less, what is the magnitude of the frictional force of the ground acting on the ladder?

A hydraulic lift has two cylindrical portions, one with a radius of 0.95 m and the other with a radius 0.25 m. Suppose there is a car of mass 1893 kg placed on the platform associated with the larger cylinder. What is the magnitude of the minimum force needed on the side of the smaller cylinder to keep the car lifted above ground? If the car is raised 0.39 m above ground, how far does the piston in the small cylinder have to move?

For the bearing specified in problem 6.11 calculate the percentage in load increase that would cause a 20 percent decrease in film thickness

A pump capable of maintaining 20 [MPa] of pressure is supplying oil of viscosity 80 [cP] to a circular hydrostatic thrust bearing of an outside diameter of 0.1 [m] at a rate of 0.4x10* [m/s], generating a steady film thickness of 30 [um]. The bearing supports a weight of 60 [kN] and rotates at 1,000 [rpm]. Calculate a suitable recess radius and pumping power. (Ans. R, = 0.0285 [m], H= 50.89 [W])

A circular hydrostatic bearing operates at the speed of 200 [rps], has a minimum film thickness of 50 [um]and supports a load of 50 [kN]. The bearing's outside radius is three times larger than the recess radius.A lubricant is delivered through the capillary length of 1 = 80 [mm] and diameter d = 0.7 [mm]. The pump supply pressure is 3 [MPa] and the lubricant's viscosity is 8.5 [cP]. Calculate bearing dimensions, friction coefficient and power loss. (Ans. R, = 0.051 [m], R = 0.154 [m], µ = 0.0005 and H = 27.32 [W])

Water passes through a main pipe with a flow rate of 7.35 m³/s. The water flow is then equally broken up into 4 smaller pipes, each of radius 25.1 cm. How fast is the water travelling the roof the smaller pipes?