Question :
26. A 15 000-N car a hydraulic lift rests a : 2102188
26. A 15 000-N car on a hydraulic lift rests on a cylinder with a piston of radius 0.20 m. If a connecting cylinder with a piston of 0.040-m radius is driven by compressed air, what force must be applied to this smaller piston in order to lift the car?
A. 600 N
B. 1 500 N
C. 3 000 N
D. 15 000 N
27. By what factor is the total pressure greater at a depth of 850 m in water than at the surface where pressure is one atmosphere? (water density = 1.0 ´ 103 kg/m3, 1 atmosphere pressure = 1.01 ´ 105 N/m2, and g = 9.8 m/s2)
A. 100
B. 83
C. 74
D. 19
28. If the column of mercury in a barometer stands at 72.6 cm, what is the atmospheric pressure? (The density of mercury is 13.6 ´ 103 kg/m3 and g = 9.80 m/s2)
A. 0.968 ´ 105 N/m2
B. 1.03 ´ 105 N/m2
C. 0.925 ´ 105 N/m2
D. 1.07 ´ 105 N/m2
29. Dams at two different locations are needed to form a lake. When the lake is filled, the water level will be at the top of both dams. The Dam #2 is twice as high and twice as wide as Dam #1. How much greater is the force of the water on Dam #2 than the force on Dam #1? (Ignore atmospheric pressure; it is pushing on both sides of the dams.)
A. 2
B. 4
C. 8
D. 16
30. Atmospheric pressure is 1.0 ´ 105 N/m2, and the density of air is 1.29 kg/m3. If the density of air is constant as you get higher and higher, calculate the height of the atmosphere needed to produce this pressure.
A. 7 900 m
B. 77 000 m
C. 1 260 m
D. 10 300 m
