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Class : 9

Subject : Science

Unit : 8.00 Lesson :Simple Machine

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1.) What is efficiency of a machine?

2.) Name the factors that affect the mechanical advantage of a machine.

3.) Define an ideal machine.

4.) What is output work?

5.) What is input work?

6.) What does the velocity ratio of a lever 3 indicate?

7.) What should be done to make a simple machine more efficient?

8.) What is indicated by efficiency of a pulley is 60%?

9.) Define a compound machine.

10.) Write the formula that is used to calculate velocity ratio of a screw.

11.) There is no gain in mechanical advantage in a single fixed pulley. Explain why the pulley is used then.

12.) In the case of block and tackle arrangement, mechanical advantage increase with the number of pulleys. Explain.

13.) Write two uses of each: inclined plane, pulley and wheel and axle.

14.) What should be done to lift the same load by applying less effort on a inclined plane?

15.) How can we say that a wheel barrow is a compound machine?

16.) Describe in short that screw and wedge are modified from the inclined plane

17.) Write a short notes one: i) effect of friction on efficiency of machine ii) velocity ratio of a machine iii) use of pulleys in our daily life iv) compound machines

18.) Differentiate between MA and VR.

19.) Differentiate between input work and output work.

20.) Differentiate between simple and compound machine.

21.) Differentiate between VR and efficiency.

22.) Differentiate between pulley and inclined plane.

23.) Differentiate between screw and wedge.

24.) The value of velocity ratio is greater than the value of mechanical advantage. Why?

25.) The value of efficiency is never 100% or more in practice. Why?

26.) Input work is always greater than output work. Why?

27.) It is easier to climb up a slanted slope than a vertical slope. Why?

28.) It is easier to lift the same load by using three-pulley system than by using two- pulley system. Why?

29.) Wheel and axle is called a continuous lever. Why?

30.) What is simple machine? Write its types.

31.) How does a simple machine help us?

32.) Define mechanical advantage (MA) of a simple machine.

33.) Actual value of MA is not same as the calculated value of it, why?

34.) V.R is also called ideal mechanical advantage, why?

35.) Value of MA is always less than VR in a simple machine, why?

36.) What do you mean by output work and input work?

37.) What is the principle of simple machine?

38.) What do you mean by an ideal machine? OR What is perfect machine?

39.) Efficiency of simple machine is always less than 100%, why?

40.) How can efficiency of a simple machine be increased?

41.) ‘No machine is perfect’ Justify this statement.

42.) “Efficiency of simple machine is 70%” What do you mean by this?

43.) How much energy will be wasted on using a simple machine with efficiency 60%? What is the reason for the wastage of energy? How can the energy-wastage be reduced?

44.) Does the use of grease affect the V.R of a machine? Explain with

45.) What is lever? Write the principle of lever.

46.) On what basis levers are classified? Mention them with examples of each.

47.) Value of MA in second class lever is always greater than one, why?

48.) In third class lever value of MA is always less than one, why?

49.) Tight knot can be opened by using long spanner, why?

50.) When load is shifted towards wheel of wheel barrow, work will be easier? Explain with reason.

51.) Define pulley and write its types.

52.) What do you mean by single fixed pulley?

53.) It is easier to work with a combined pulley than a fixed pulley, why?

54.) What is inclined plane? It is called a simple machine, why?

55.) Mountainous roads are made longer and sloping, why?

56.) Define the terms screw and pitch.

57.) What is wheel and axle?

58.) Wheel and axle is called continuous lever, why?

59.) What is a wedge? Give some examples.

60.) What do you mean by moment of force? What are the factors affecting it?

61.) How is moment of force measured?

62.) How is moment of force calculated in following conditions?

63.) State law of moment of force.

64.) A tall tree has greater probability of breaking than a short tree in a storm, why?

65.) The probability of breaking a branch of tree is more when a person moves along it towards its end, why?

66.) The handle is fixed on the outside edge of a door, why?

67.) Long spanner is used to open rusted knot, why?

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