A vertical piston-cylinder device contains a gas at a pressure of 100 kPa. The piston has a mass of 10 kg and a diameter of 14 cm. Pressure of the gas is to be increased by placing some weights on the piston. Determine the local atmospheric pressure and the mass of the weights that will double the pressure of the gas in the cylinder. Answer: 93.6 kPa, 157 kg

The piston of a vertical piston-cylinder device containing a gas has a mass of 60 kg and a cross-sectional area of 0.04 m $^2$, as shown. The local atmospheric pressure is 0.97 bar, and the gravitational acceleration is 9.81 m / s $^2$.

(a) Determine the pressure inside the cylinder.

(b) If some heat is transferred to the gas and its volume is doubled, do you expect the pressure inside the cylinder to change?

An object whose mass is 100 kg is located 20 m above a datum level in a location where standard gravitational acceleration exists. Determine the total potential energy, in kJ, of this object.

Water is pumped from a lake to a storage tank 15 m above at a rate of 70 L/s while consuming 15.4 kW of electric power. Disregarding any frictional losses in the pipes and any changes in kinetic energy, determine (a) the overall efficiency of the pump–motor unit and (b) the pressure difference between the inlet and the exit of the pump.

Air is contained in a vertical piston–cylinder assembly such that the piston is in static equilibrium. The atmosphere exerts a pressure of $\hspace{1mm} 101 kPa \hspace{1mm}$ on top of the $\hspace{1mm} 0.5$-m-diameter piston. The gage pressure of the air inside the cylinder is $\hspace{1mm} 1.2 kPa$. The local acceleration of gravity is $\hspace{1mm} g=9.81 \hspace{1mm} m/s^2$. Subsequently, a weight is placed on top of the piston causing the piston to fall until reaching a new static equilibrium position. At this position, the gage pressure of the air inside the cylinder is $\hspace{1mm} 2.8 kPa$. Determine

(a) the mass of the piston, in kg, and

(b) the mass of the added weight, in kg.

Consider a double- fluid manometer attached to an air pipe. If the specific gravity of one fluid is 13.55, determine the specific gravity of the other fluid for the indicated absolute pressure of air. Take the atmospheric pressure to be 100 kPa. Answer: 1.59

A vertical, frictionless piston-cylinder device contains a gas at 180 kPa absolute pressure. The atmospheric pressure outside is 100 kPa, and the piston area is 25 cm^2. Determine the mass of the piston.

A gas is contained in a vertical, frictionless piston– cylinder device. The piston has a mass of 3.2 kg and a cross-­sectional area of $35 cm^2.$ A compressed spring above the piston exerts a force of 150 N on the piston. If the atmospheric pressure is 95 kPa, determine the pressure inside the cylinder.

Suppose y varies directly as x. Write a direct variation equation that relates x and y. Then solve. If y = 15 when x = 12, find y when x = 32.

The average temperature of the atmosphere in the world is approximated as a function of altitude by the relation $T_{\text{atm}}$= 288.15 - 6.5z, where $T_{\text{atm}}$ is the temperature of the atmosphere in K and z is the altitude in km with z = 0 at sea level. Determine the average temperature of the atmosphere outside an airplane that is cruising at an altitude of 12,000 m.

How would you define a system to determine the temperature rise created in a lake when a portion of its water is used to cool a nearby electrical power plant?

The basic barometer can be used to measure the height of a building. If the barometric readings at the top and at the bottom of a building are 675 and 695 mmHg, respectively, determine the height of the building. Take the densities of air and mercury to be 1.18 kg/m^3 and 13,600 kg/m^3, respectively.

A pressure cooker cooks a lot faster than an ordinary pan by maintaining a higher pressure and temperature inside. The lid of a pressure cooker is well sealed, and steam can escape only through an opening in the middle of the lid. A separate metal piece, the petcock, sits on top of this opening and prevents steam from escaping until the pressure force overcomes the weight of the petcock. The periodic escape of the steam in this manner prevents any potentially dangerous pressure buildup and keeps the pressure inside at a constant value. Determine the mass of the petcock of a pressure cooker whose operation pressure is 120 kPa gage and has an opening cross-sectional area of $3 mm^2$. Assume an atmospheric pressure of 101 kPa, and draw the free-body diagram of the petcock.

The average temperature of the atmosphere in the world is approximated as a function of altitude by the relation $T_{\mathrm{atm}}=288.15-6.5 z$ where $T_{\mathrm{atm}}$ is the temperature of the atmosphere in K and z is the altitude in km with z = 0 at sea level. Determine the average temperature of the atmosphere outside an airplane that is cruising at an altitude of 12,000 m.