1st Year Physics Chapter 4 Work and Energy Notes MCQs Bank

physics 11th notes Chapter 4

1. The propulsion force of a rocket is?


2. Gravitational P.E of a body can be found by?


3. When a force is parallel to the direction of motion of the body, then work done on the body is:


4. One megawatt-hour is equal to?


5. The power output of a lamp is 6W. How much energy does the lamp give out in 2 minutes?


6. The escape velocity from the earth’s surface in kms⁻¹ is about?


7. The center of the Sun produces large amounts of energy, what is the source of this energy?


8. Work-energy equation can be expressed as:


9. A field in which the work is done in moving a body in a closed path is zero is called?


10. We get energy from food during a day which is equivalent to the energy obtained from _______ liter petrol?


11. The source of geothermal energy is.


12. An elevator weighing 3.5×10¹⁰ N is raised to a height of 1000m in the absence of friction, the work done is?


13. The escape velocity of a body in the gravitational field of Earth is independent of?


14. Geothermal energy is a __________source of energy.


15. ________ cell converts solar energy into electrical energy.


16. The SI unit of power is


17. The source of tidal energy is?


18. Two bodies of 4g and 16g have the same K.E. What is the ratio of their momentum?


19. Proton, electron and neutron and α particles have same momentum. Which of them have highest K.E?


20. The tides raise the mater in the sea roughly in a day:


21. From which source would the release of energy be affected by the change in the earth’s gravitational field?


22. The energy stored in the spring of a watch is:


23. The work done is said to be negative when force and displacement are


24. Work done by a variable force is determined by dividing?


25. If a body a mass of 2 kg is raised vertically through 2m, then the work done will be?


26. Area under the curve of force-displacement graph is equal to:


27. Which of the following types of force can do no work on the particle on which it acts?


28. One mega watt hour is equal to.


29. Work done will be maximum if the angle between the force F and displacement d is?


30. Slope of work time graph is equal to.


31. A tennis ball is dropped on to a horizontal surface. As the ball bounces up and down, the height of each bounce gradually decreases, during the motion of the ball?


32. The average power and instantaneous power become equal if work is done at.


33. Work has the dimension as that of same as that of.


34. The relation between horse power and watt is.


35. Work done by the force of friction is.


36. When a force is perpendicular to the direction of motion of the body, then work done on the body is?


37. The temperature of hot igneous rocks is about?


38. Which of the following is not a conservative force?


39. Work done on the body equals?


40. Does work have the dimension as that of the same as that of?


41. Power is also defined as dot product of


42. The original source of tidal energy is:


43. If the Moon radius is 1600 km and g on its surface is 1.6 ms⁻², then the escape velocity on the moon is?


44. A field will be conservative when work done:


45. One kilowatt hour of work is equal to


46. If velocity is doubled, then?


47. Escape velocity depends upon the radius of Earth. Which one shows its proper dependence?


48. The highest value of escape velocity in the solar system is for the planet?


49. The work done by the force of 10N applied parallel to direction of motion up to 20 m


50. When two protons are brought close, their?


51. The pull of the Moon can distort the continents by pulling and up and down by as much as?


52. The consumption of energy by 60 watt bulb in 2 seconds is:


53. When an arrow is released from its bow, its energy is transformed from?


54. A car is driven along a level road. The total energy input from petrol is 60kJ and the car wastes 45kJ of energy, what is the efficiency of the car?


55. The relation between the escape velocity Vesc and orbital speed Vo is given by?


56. If mass of a moving object is doubled, its K.E becomes:


Short Questions

1. A ball of mass m is held at a height hy above a table. The table top is at a height h above the floor. One student says that its P.E is mgh, and other says that P.E is mg (h₁+ h₂). Who is correct?
2. A ball of weight 98N is moving on a friction-less surface with velocity of 1 ms⁻¹ Compute its K.E.
3. A body of 1 kg is lifted to a height of 10m above the ground whan is the work done on the body?
4. A boy uses a catapult to throw a stone which accidentally smashes a green house window.List the possible energy changes?
5. A bucket is taken to the bottom of a well does the bucket possess any potential energy?
6. A car moving with constant speed along a level road with no net force acting on it.Is any work being done on the car?
7. A diver of 50g mass dives from a 10m high diving board in a swimming pool.Calculate its P.E before jump?
8. A girl drops a cup from a certain height which breaks into pieces. What energy changes are involved?
9. A man rowing boat upstream is at rest with respect to shore is he doing work?
10. A masons of 100N weight is climbing on a 10 m high ladder.Find his P.E.at the middle of ladder?
11. A meteor when enters into Earth’s Atmosphere burns.What happens to its energy and momentum?
12. A person holds a bag of groceries while standing still talking to a friend.A car is stationary with its engine running.From the standpoint of work how are these two situations similar?
13. A person holds a bag of groceries while standing still. A car is stationary with its engine running. How are the two situations similar from the point of view of work?
14. An object has one joule of potential energy Explain what it means.
15. At what point the energy of a swinging pendulum is wholly potential.Where is its K.E maximum?
16. Calculate the work done in kilo joules in lifting a mass of 10 kg
17. Calculate the work done in kilo joules in lifting a mass of 10kg through a vertical height of 10m?
18. Define conservative and non-conservative fields.
19. Define conservative field. Give its example.
20. Define joule and watt.
21. Define power. Write its SI unit.
22. Define work and its SI unit.
23. Describe some uses of solar cells?
24. Describe the methods to obtain solar energy?
25. Differentiate between renewable and non-renewable resources of energy?
26. Distinguish between average power and instantaneous power?
27. Due to smaller value of ‘g’a man can jump higher on the surface of the moon.Can he run faster on the account?
28. Explain briefly about residual heat of the earth.
29. Explain interconversion of P.E and K.E.
30. Find the average power in lifting 100kg of mass in 1 s up to height of 10 m?
31. How can the waste products be converted into useful energy?
32. How can we gain energy from tides?
33. How can we gain energy from tides? Or What is tidal energy? Or How energy can be obtained from sea tides? Explain briefly.
34. How can we gain the energy from waves?
35. How electrical energy can be obtained from sunlight by indirect conversion method?
36. How energy is obtained from direct combustion and fermentation.
37. How many most common methods can be used for the conversion of bio mass into fuel? Write their names.
38. How sunlight is directly converted into electricity by solar cells?
39. How you can get energy from the waves?
40. In which case is more work done? When 50kg bag of book is lifted through 50 cm,or when 50kg crate is pushed through 2m across the floor with a force of 50N?
41. Is kinetic energy a vector quantity?
42. Name some non-conventional energy sources.
43. Name two conservative forces?
44. Show that work done against frictional force is negative?
45. State law of conservation of energy?
46. The force between a pair of protons is that of repulsion.Does the P.E increase as the protons are brought closer?
47. What are common methods to convent biomass into energy?
48. What are conservative and non-conservative forces? Give the examples of non-conservative force. Define non-conservative field?
49. What are non-conventional energy sources? Describe briefly.
50. What are the essential conditions for conservative field?
51. What do you mean by non conventional energy sources?
52. What do you mean by variable force? Give its two examples?
53. What four conclusions can you draw from the definition of work?
54. What happens to the kinetic energy of a bullet when it penetrates into a target
55. What is absolute potential energy?
56. What is dimension of power, also define power.
57. What is geothermal energy? How is it generated?
58. What is meant by conservative field?
59. What is meant by Dissipation of energy?
60. What is meant by kwh i.e.Show that kwh=3.6 MJ
61. What is solar energy?What is the function of solar cells?
62. What is the dimension of power?
63. What sort of energy is in the following? (a)Compressed spring (b) Water in a high dam (c) A moving car
64. What sort of energy is in the following? Compressed spring, Water in a high dam,
65. What type of energy is stored in the spring of watch?
66. What type of energy is stored in water dam?
67. When a rocket re-enters the atmosphere the nose cone becomes very hot,where does this energy come from?
68. When an arrow is shot from its bow it has kinetic energy.From where does it get the K.E.?
69. Why does the bob of a swinging pendulum come to rest after some time?
70. Write the expression of work done by a force that acts at an angle 60ᵒ to a moving body?

Long Questions

1. Define escape velocity and write its formula?
2. When an arrow is shot from its bow? It has K.E. From where does it get the kinetic Energy? Define absolute potential energy?
3. What is meant by Non-conventional energy sources? Mention four of these energy sources?
4. Define work. Explain when it is maximum and when it is zero?
5. What is solar energy? How sunlight can be converted into electrical energy?
6. Define conservative and non-conservative forces?
7. When a body is dropped from a height 4m, calculate its velocity?
8. Define work energy principle. Also write down its equations.
9. What happens to the K.E of a bullet when it penetrates into bag of sand?
10. How can you calculate work done by a force acting on an object from force displacement graph?
11. Explain work done by variable force.
12. What is conservative field? Explain work done by gravitational force.
13. Explain that work done in gravitational field is independent of path followed.
14. State and explain absolute potential.
15. Define escape velocity. Derive mathematical expression for escape velocity.
16. State and explain law of conservation of energy.
17. Explain inter-conversion of K.E into P.E, when frictional forces are not present.
18. Discuss in detail the inter-conversion of kinetic and potential energy.
19. A man pushes a lawn mower with a 40N force directed at a angle of 20 degree downward from the horizontal. Find the work done by the man as he cuts a strip of grass 20m long.
20. A rain drop m = 3.35 x 10⁻⁵ kg falls vertically at a constant speed under the influence of the forces of gravity ad friction. In falling through 100m, how much work is done by: (a) Gravity: (b) Friction:
21. Ten bricks each 6cm thick and mass 1.5kg, lie flat on a table. How much work is required to stack them one on the top of another.
22. A car of mass 800kg traveling at 54kmh⁻¹ is brought to rest in 60 meters. Find the average retarding force on the car. What has happened to the original K.E?
23. A 1000kg automobile at the top of an inclined plane 10m high and 100m long is released and rolls down the hill. What is its speed at the bottom of inclined if the average retarding force due to friction is 480N?
24. If 100m³ of water is pumped from a reservoir into a tank, 10 m higher than the reservoir, in 20 minutes. If density of water is 1000kg/m³, find (a) The increase in P.E (b) The power delivered by pump.
25. A force(thrust) of 400N is required to overcome road friction and air resistance in propelling an automobile at 80kmh⁻¹. What power kW must the engine develop?
26. How large a force is required to accelerate an electron (m 9.1 x 10⁻³¹kg) from rest to a speed of 2 * 10(7)ms⁻¹) through a distance of 5cm.
27. A diver weighing 750N dive from a board 10m above the surface of a pool of water. Use the conservation of mechanical energy to find the speed at a point 5m above the water surface, neglecting air friction.
“28. A child starts from the rest at the top of a slide of height 4m.
(a) What is his speed at the bottom if the slide is friction less?
(b) If he reaches the bottom, with a speed of 6 ms⁻¹. What percentage of his total energy at the top of the slide is lost as a result of friction?”

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