Question

7. A solid sphere of copper ( 8940 kg/m') with a radius of 5.0 cm has a mass of a) 45 9 kg b) 6.78 kg c) 25.7 kg d) 4.68 kg (10 pts) The pressure at the bottom of a 76-cm high column of mercury (p = 13,550 kg/m) is a) 0.010 kPa b) 101 kPa c) 10.1 kPa d) 0.101 kPa (10 pts) 9. Anaxial force of 20 kN acts on a 1.50-cm diameter rod. The axial stress is a) 6.81 MPa b) 40 MPa c) 113 MPa d) 1.13 MPa (10 pts) 10. A box of mass 30 kg hangs from two cables as shown. Find the tension force in cable AB (10 pts) II. A steel ( E 200 GPa) rod with a diameter of 1.25 cm is subjected to an axial force of 10KN If the length of the rod is 20 cm, the axial deformation of the rod is a) Imm b) 0.810 mm s) & 10 mm d) 0.18 mm (10 pts) 12. Water flows through a pipe with an inside diameter of 20.0 cm at velocity of 5 ms. The Reynolds number is a) 510 b) 101 c) 10 x 10 d) 1.0 x 10 (10 pts)

Answer 1

Solution 1

Density of copper = d = 8940kg/m3

Volume of sphere = (4/3) πr​​​​​3

r = 5cm = 0.05m

Volume V = (4/3) π (0.05)3

We know that, mass = volume x density

m = 5.236 x 10-4 x 8940

So, mass m = 4.681 kg

hence, option d is correct.

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