Class 11 Physics NEB Past Questions

1. Define centripetal force. Derive its expression.

2. A body of mass 0.2 kg is whirled in a horizontal circle of radius 0.5m by a string inclined at 30° to the vertical. Calculate i. the tension in the string ii. the speed of the mass in the horizontal circle.

3. What is meant by banking of a road? Discuss the motion of a vehicle round a banked circular track and obtain an expression for the banking angle in terms of speed of the vehicle.

4. An iron block of mass 10 kg rests on a wooden plane inclined at 30° to the horizontal. It is found that the least force parallel to the plane which causes the block to slide up is 100N. Calculate the coefficient of friction between the two surfaces.

5. A chair of mass 10kg is sitting on a horizontal floor which is not frictionless. You push on the chair with a constant force of magnitude 30N which is directed at an angle of 30° below the horizontal and chair slides on the floor. Draw free-body diagram and calculate normal force that the floor exerts on the chair.

6. Define linear momentum. Show that principle of conservation of linear momentum can be verified by using Newton's laws.

7. Define angle of friction and angle of repose. Establish a relation between them.

8. Define elastic limit and Young's modulus of elasticity. How can you determine the Young's modulus for a material in the laboratory? Explain.

9. A force of 20 N applied to the ends of a wire 4 m long produces an extension of 0.24 mm. If the diameter of wire is 2 mm, calculate the stress on the wire, its strain and the value of the Young's modulus.

10. Why are steel rods embedded in concrete in a house roofs? Explain.

11. A copper wire and a steel wire of the same cross sectional area and of length 1m and 2m respectively are connected end to end. A force is applied, which stretches their combined length by 1cm. Find how much each wire is elongated.

12. When will you attract the sun more, today at noon or tonight at midnight? Justify your answer.

13. Calculate the amount of work done to move 1 kg mass from the surface of the earth to a point 10⁵ km from the centre of the earth.

14. A remote sensing satellite of the earth revolves in a circular orbit at a height of 250 km above the earth's surface. What is the orbital speed and period of revolution of the satellite?

15. An artificial satellite revolves round the earth in 3 hours in a circular orbit. Find the height of the satellite above the earth assuming earth as a sphere of radius 6370 km.

16. What is escape velocity? Derive an expression for it on the surface of the earth.

17. A person sitting in an artificial satellite of the earth feels weightlessness, but a person standing on moon has weight through the moon is a satellite of the earth. Why?

18. If the earth suddenly stops rotating about its axis, what would be the effect on 'g'? Would this effect be the same at all places?

19. A stone on the top of a vertical cliff is kicked horizontally so that its initial velocity is 9 ms⁻¹. If the cliff is 200 m high, calculate (i) time taken by stone to reach the ground (ii) How far from the bottom of the cliff the stone will hit the ground?

20. From a flying aeroplane a body should be dropped in advance to hit the target, why?

21. What is a projectile? Show that its path is parabolic and obtain expression for maximum vertical height, time of flight and horizontal range.

22. If the distance travelled by a body in time t is given by x = at + bt², then what will be the acceleration of the body?

23. In Vander Waal's equation $\left(P+\frac{a}{V^2}\right)(V-b)=RT$, what are the dimensions of constants $a$ and $b$?

24. Distinguish between precise and accurate measurements.

25. What do you mean by dimensional formula of a physical quantity? Write the dimensional formula of power.

26. The energy of a photon is given by $E=hf$. Find the dimension and unit of Planck's constant $h$, where $f$ is the frequency of radiation.

27. What are real and apparent expansions of a liquid? Obtain the relation between coefficient of real and apparent expansion of liquid.

28. A glass flask of volume 400cm³ is just filled with mercury at 0°C. How much mercury will overflow when the temperature of the system rises to 80°C. The coefficient of cubical expansion of glass is 1.2 × 10⁻⁵ °C⁻¹ and that of mercury is 1.8 × 10⁻⁵ °C⁻¹.

29. At what temperature wood will just sink in benzene if their densities at 0°C are 8.8×10² kg/m³ and 9×10² kg/m³ respectively. [γbenzene = 1.2 × 10⁻³ K⁻¹ and γwood = 1.5 × 10⁻⁴ K⁻¹]

30. Why does a thick glass cup crack when boiling water is poured on it in the winter? Explain.

31. If (\(\vec{A}\)) and (\(\vec{B}\)) are non-zero vectors, is it possible for (\(\vec{A}\)) x (\(\vec{B}\)) and (\(\vec{A}\)).(\(\vec{B}\)) both to be zero? Justify your answer.

32. If (\(\vec{B}\)) is added to (\(\vec{A}\)), under what condition does the resultant vector have magnitude equal to (\(\vec{A}\)) + (\(\vec{B}\))?

33. A body is moving with constant velocity v along a circular path of radius r. How much work is done by the centripetal force in revolving the body?

34. A light body and a heavy body have the same momentum. Which one will have greater kinetic energy? Explain.

35. Since the moon is constantly attracted towards the earth by the gravitational interaction, why does it not crash into the earth?

36. Two bodies of different masses are moving with the same kinetic energy of translation, which one has more momentum?

37. State principle of conservation of energy and prove it.

38. Differentiate between conservative and non-conservative forces.

39. What is a conical pendulum? Obtain an expression for its time period.

40. A stone tied at one end of a string is whirled in a vertical circle. Where will the tensions in the string be maximum and minimum? Show them in a diagram.