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(b It stays the same (c) It rises (d) It cannot be determined 20 6. An alloy of

ID: 2031999 • Letter: #

Question

(b It stays the same (c) It rises (d) It cannot be determined 20 6. An alloy of copper and gold displaces 1.935 cm2 of water. It has a mass of 3.44 g If gold has a density of 19.3 g/cm and copper has a density of 8.9 g/em, what is the percent of gold by mass in the object? (a) 45% (b) 60% (c) 75% (d) 90% 7. What is the hydrostatic pressure on a diver at a depth of 1 km in sea water? 1 atm 1.01 x 103 N/m2, the density of sea water is 1.03 x 10 kg/m3, g-9.81 m/s (a) 99 atm (b) 100 atm (c) 101 atm (d) 110 atm 8. A 200 N girl stands on one platform a hydraulic press. The platform is a square with a width of 0.5 m. How much mass can she balance sitting on the other square platform of the press with a width of 4 m? (a) 648 kg (b) 1306 kg (c) 6592 kg (d) 10368 kg

Explanation / Answer

7.

Pressure = Patm + rho*g*h

Patm = 1 atm = 1.01*10^5 N/m^2

h = 1 km = 1000 m

rho = 1030 kg/m^3

g = 9.8 m/sec^2

P = 1.01*10^5 + 1030*9.81*1000

P = 10205300 N/m^2 = 100.7 atm = 101 atm

Correct option is C.

8.

Pressure = Force/Area

P = F/A

F = P*A

If Pressure is same, then Force is directly proportional to Area

F2/F1 = A2/A1

F2 = F1*(A2/A1)

F = m*g

A = w^2

m2*g = m1*g*(w2^2/w1^2)

m2 = (200/9.8)*(4/0.5)^2

m2 = 1306 kg

Correct option is B.