Physics 11th Class Book Pdf
ANSWERS
391
ANSWERS
Chapter 9
9.1 9.2
1.8 (a) From the given graph for a stress of 150 × 106 N m-2 the strain is 0.002 (b) Approximate yield strength of the material is 3 × 108 N m-2
9.3
(a) Material A (b) Strength of a material is determined by the amount of stress required to cause fracture: material A is stronger than material B.
9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 9.12 9.13 9.14 9.15 9.16
(a) False
(b)
True
1.5 × 10-4 m (steel); 1.3 × 10-4 m (brass) Deflection = 4 × 10–6 m 2.8 × 10-6 0.127 7.07×10 N Dcopper/Diron = 1.25 1.539 × 10-4 m 2.026 × 109 Pa 1.034 × 103 kg/m3 0.0027 0.058 cm3 2.2 × 106 N/m2
4
392
PHYSICS
9.17 9.18 9.19 9.20 9.21
Pressure at the tip of anvil is 2.5 × 1011 Pa (a) 0.7 m (b) 0.43 m from steel wire
Approximately 0.01 m 260 kN 2.51 × 10–4 m3
Chapter 10 (a) decreases (b) η of gases increases, η of liquid decreases with temperature (c) shear strain, rate of shear strain (d) conservation of mass, Bernoulli’s equation (e) greater. 6.2 × 106 Pa 10.5 m Pressure at that depth in the sea is about 3 × 107 Pa. The structure is suitable since it can withstand far greater pressure or stress. 6.92 × 105 Pa 0.800
10.3 10.5 10.6 10.7 10.8 10.9
10.10 Mercury will rise in the arm containing spirit; the difference in levels of mercury will be 0.221 cm. 10.11 No, Bernoulli’s principle applies to streamline flow only. 10.12 No, unless the atmospheric pressures at the two points where Bernoulli’s equation is applied are significantly different. 10.13 9.8 × 102 Pa (The Reynolds number is about 0.3 so the flow is laminar). 10.14 1.5 × 103 N 10.15 Fig (a) is incorrect [Reason: at a constriction (i.e. where the area of cross-section of the tube is smaller), flow speed is larger due to mass conservation. Consequently pressure there is smaller according to Bernoulli’s equation. We assume the fluid to be incompressible]. 10.16 0.64 m s-1 10.17 2.5 × 10-2 N m-1 10.18 4.5 × 10-2 N for (b) and (c), the same as in
391
ANSWERS
Chapter 9
9.1 9.2
1.8 (a) From the given graph for a stress of 150 × 106 N m-2 the strain is 0.002 (b) Approximate yield strength of the material is 3 × 108 N m-2
9.3
(a) Material A (b) Strength of a material is determined by the amount of stress required to cause fracture: material A is stronger than material B.
9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 9.12 9.13 9.14 9.15 9.16
(a) False
(b)
True
1.5 × 10-4 m (steel); 1.3 × 10-4 m (brass) Deflection = 4 × 10–6 m 2.8 × 10-6 0.127 7.07×10 N Dcopper/Diron = 1.25 1.539 × 10-4 m 2.026 × 109 Pa 1.034 × 103 kg/m3 0.0027 0.058 cm3 2.2 × 106 N/m2
4
392
PHYSICS
9.17 9.18 9.19 9.20 9.21
Pressure at the tip of anvil is 2.5 × 1011 Pa (a) 0.7 m (b) 0.43 m from steel wire
Approximately 0.01 m 260 kN 2.51 × 10–4 m3
Chapter 10 (a) decreases (b) η of gases increases, η of liquid decreases with temperature (c) shear strain, rate of shear strain (d) conservation of mass, Bernoulli’s equation (e) greater. 6.2 × 106 Pa 10.5 m Pressure at that depth in the sea is about 3 × 107 Pa. The structure is suitable since it can withstand far greater pressure or stress. 6.92 × 105 Pa 0.800
10.3 10.5 10.6 10.7 10.8 10.9
10.10 Mercury will rise in the arm containing spirit; the difference in levels of mercury will be 0.221 cm. 10.11 No, Bernoulli’s principle applies to streamline flow only. 10.12 No, unless the atmospheric pressures at the two points where Bernoulli’s equation is applied are significantly different. 10.13 9.8 × 102 Pa (The Reynolds number is about 0.3 so the flow is laminar). 10.14 1.5 × 103 N 10.15 Fig (a) is incorrect [Reason: at a constriction (i.e. where the area of cross-section of the tube is smaller), flow speed is larger due to mass conservation. Consequently pressure there is smaller according to Bernoulli’s equation. We assume the fluid to be incompressible]. 10.16 0.64 m s-1 10.17 2.5 × 10-2 N m-1 10.18 4.5 × 10-2 N for (b) and (c), the same as in