1) A geologist finds that a moon rock whose mass is 9.14 kg has an apparent mass
ID: 2119800 • Letter: 1
Question
1) A geologist finds that a moon rock whose mass is 9.14 kg has an apparent mass of 5.10 kg when submerged in water. What is the density of the rock? 2) A spherical balloon has a radius of 6.60 m, and is filled with helium. How large a cargo can it lift, assuming that the skin and structure of the balloon have a mass of 930 kg? Neglect the bouyant force on the cargo volume itself. 3) What is the volume rate of flow of water from a 1.97 cm diameter faucet if the pressure head is 14.4 m? 4) What is the lift (in newtons) due to Bernoulli's principle on a wing of area 72.4 m2 if the air passes over the top and bottom surfaces at speeds of 273 m/s and 169 m/s, respectively? 5) A 2.13 N force is applied to the plunger of a hypodermic needle. If the diameter of the plunger is 1.32 cm and that of the needle 0.194 mm, with what force does the fluid leave the needle? What force on the plunger would be needed to push fluid into a vein where the gauge pressure is 16.5 mm-Hg? Answer for the instant just before the fluid starts to move. 6) How high should the pressure head be if water is to come from a faucet at a speed of 8.86 m/s? Ignore viscosity.Explanation / Answer
5) The pressure applied is Force/Area = 2.13/pi*(1.32/2)^2. The same pressure exists over the smaller area of the needle, F = P*A = 2.13/pi*(1.32/2)^2 * pi*(0.0165/2)^2
F = 2.13*0.0165^2/1.32^2
F = 1.01*10^-3 N
The pressure in the fluid is the same, so F/pi*(.0132/2)^2 = 16.5 mmHg = 2000 N/m^2
F = pi*(.0132/2)^2*2000 = 0.234 N
6)mgh = 1/2 mv^2
=> gh = 1/2 v^2
=> h = 1/2* v^2/g
Given, v= 8.86 m/s and taking g = 9.8 m/s^2, we get:
h = 1/2 * 8.86 * 8.86 / 9.8
Thus, height = 4.005 m
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