WINTER BREAK HOLIDAY HOME WORK DECEMBER- 2017
CLASS XI-A SUBJECT-PHYSICS
- What Is a restoring force?
- Define young’s modulus of elasticity. Write dimensions of young’s modulus
- What is the value of modulus of rigidity for an incompressible liquid?
- A wire fixed at the upper end stretches by length l by applying a force F. What is the work done in stretching the wire?
- The young’s modulus of a wire of length L and radius r is Y. If the length is reduced to L/2 and radius r/4, what will be its Young’s modulus?
- How does the young’s modulus change with the rise of temperature?
- Which one is more elastic rubber or steel?
- Define stress and strain and derive their units. Write any two limitations of Hooke’slaw.
- If S is the stress and Y is young’s modulus of the material of the wire, what is the energy stored in the wire per unit volume in terms of S and Y.
- Define the terms Young’s modulus, bulk modulus and modulus of rigidity. Also give their units and dimensions.
- .Draw the stress strain graph for a metal wire find the following points on the curve
(a)proportionality limit (b)elastic limit (c)yield point and (d) permanent set.
- Determine the Poisson’s ratio of the material of a wire whose volume remains constant under an external normal stress.
13. What is the value of bulk modulus for an incompressible liquid?
14. What is meant by elastic fatigue?
15. Ramesh went with his friend Atul on a long drive. He saw a notice “use of bridge is not safe”. Ramesh asked Atul the reasons. Atul explained the reasons why the bridges are declared unsafe after a long time. Ramesh got satisfied.
(I)What Atul told about the unsafe bridge?
(II)A hard wire is broken by bending it repeatedly in opposite direction. Why?
(III)What according to you, are the values displayed by Atul?
16.under what condition the restoring forces are equal and opposite to external deforming forces?
17.Why are Girders I Shaped?
18. The length of a wire is cut to half. What will be the effect on the increase in its length, under a given load?
19.Nikita and her mother were going to purchase certain things. They saw a crane on the road lifting the heavy weights. Nikita asked her mother, what is the basis of deciding the thickness of metallic ropes used in cranes? Her mother was a science teacher explained her in detail.
(i)What explanation was given by Nikita’s mother?
(ii)Why springs are made of steel and not of copper?
(iii)What are the values that are associated with Neeta’s mother?)
20.Determine the force required to double the length of a steel wire of area of cross section 5x10-5 m2.Y for steel=2 x1011 N/m2.
21.A wire of length L and area of cross section A is stretched through a certain length l. If Y is the Young’s modulus of the wire, what is the force constant of the wire.
22.A cable is cut to half of its originallength. Why this change has no effect on the max. load ,the cable can support
23. A stress of 1kg /sq mm. is applied to a wire of which Young’s modulus is 1011Nm-2. Find the % increase in its length.
24. Prove that elastic energy density is equal to ½ x stress x strain.
25.What is Bernoulli’s theorem? What are its assumptions? Derive the expression for it. What are its various
limitations?
26. The fig (a) & (b) refer to the steady flow of a non-viscous liquid which of the two figures is incorrect? Why?
27. During blood transfusion the needle is inserted in a vein where gauge pressure is pg and atmospheric pressure is p. At what height must the blood container be placed so that blood may just enter the vein? Given density of blood isϬ.
28. What is Venturimeter? On which principle it works? How is it used to measure the rate of flow of the liquid flowing through the pipe?
29.During blood transfusion, the needle is inserted in a vein where the gauge pressure is 2000 Pa. at what height must the blood container be placed so that blood may just enter the vein? (use the density of whole blood from table)
30.Show that there is always an excess pressure on the concave side of the meniscus of a liquid. Obtain an expression for the excess pressure inside
a liquid drop (ii) soap bubble (iii) air bubble inside a liquid
31. Derive an expression for the ascent of a liquid in a capillary tube.
A capillary of radius 0.05 cm is immersed in water. Find the value of rise of water in capillary if value for the surface tension is 0.073 N/m and angle of contact is 00
32. Explain why?
- Blood pressure in humans is greater at the feet than the brain.
- Atmospheric pressure at a height of about 6 km decreases to nearly half its value at the sea level through the height of the atmosphere is more than 100 km
33. Rohit is planting seeds in the land. He knows the importance of digging the land before planting the seeds. Due to this plant grows properly.
- What is the characteristic of Rohit?
- What is the need of digging the field before planting seeds?
34. The lower end of a capillary tube of diameter 2.00 mm is dipped 8.00 cm below the surface of water in a beaker. What is the pressure required in the tube in order to blow a hemispherical bubble at its end in water? The surface tension of water at temperature of the experiments is 7.30 10-2 Nm-1.1 atmospheric pressure = 1.01 105 Pa, density of water = 1000 kg/m3, g = 9.80 m s-2. Also calculate the excess pressure.
35. Derive the relation between surface tension and surface energy
36. 1.State and prove equation of continuity.
2. State and explain Pascal law.
3. State stokes law. Give the numerical constant in Stokes’ law as 6Π.obtain this law from definition of viscosity.
37. How is Pascal’s law affected in the presence of gravity?
38. Kamal helps others. Once, hand of his friend got wounded. He went to a doctor and an infection of tetanus is given to his friend.
i)What values do you appreciate in Kamal?
ii)The nurse filled two syringes of different bores. Diameter of smaller syringe is 2.0 cm and of larger piston is 3.0 cm. Which syringe will hurt more to his friend if the same force is applied on both?
39. Define coefficient of thermal conductivity and write its unit. Discuss two applications of thermal conductivity in daily life.
40. What amount of heat must be supplied to 2.0 × 10–2kg of nitrogen (at room temperature) to raise its temperature by 45 °C at constant pressure? (Molecular mass of N2= 28;R= 8.3 J mol–1K–1.)
41. What do you mean by coefficient of linear expansion, coefficient of superficial expansion and coefficient of cubical expansion? Give their units. Find the relation between them.
42. Discuss different phases of water from its isotherms at temperatures both below and above its critical temperature.
43. State the Newton’s law of cooling . Explain and draw its cooling curves.