A 3 kg cylinder has radius 5 cm and height 10 cm. The cylinder is immersed
vertically into a liquid with density 1000 kg m^-3 . The top surface of the
cylinder is at a depth of 3 m.
(a) What is the pressure on the upper surface of the cylinder?
(b) What is the pressure on the lower surface of the cylinder?
(c) What is the resulting net force acting on the cylinder?
physics about pressure
2010-04-05 1:44 am
回答 (1)
2010-04-05 7:24 am
✔ 最佳答案
(a) Pressure on upper surface = 1000g x 3 N/m2 = 30 000 N/m2where g is the acceleration due to gravity, taken to be 10 m/s2
(b) Pressure on lower surface = 1000g x (3+10/100) N/m2 = 31 000 N/m2
(c) Thrust on top surface
= 30000 x (pi x 0.05^2) N
Thrust on bottom surface = 31000 x (pi x 0.05^2) N
Net upward thrust = (31000 - 30000) x (pi x 0.05^2) N = 7.85 N
Hence, net downward force = (3g -7.85) N = 22.15 N
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