75 + Interview Questions in MACHINES IN GENERAL AWARENESS Page 2 InterviewSolution

51.	With reference to the terms Mechanical Advantage, Velocity Ratio and efficiency of a machine, name and define the term that will not change for machine of a given design.
Answer» Velocity ratio. It is the ratio of the velocity of effort to the velocity of load. V.R. = VE / VL Velocity ratio does not change.

51.

With reference to the terms Mechanical Advantage, Velocity Ratio and efficiency of a machine, name and define the term that will not change for machine of a given design.

Answer»

Velocity ratio.

It is the ratio of the velocity of effort to the velocity of load. V.R. = VE / VL Velocity ratio does not change.

52.	With reference to the terms mechanical advantage, velocity ratio and efficiency of a machine, name the term that will not change for a machine of a given design.
Answer» The term is velocity ratio as M.A depends on load to be raise and effort applied keep on changing and Efficiency also changes due to friction between pulley and string and also pulley and axle.

Discussion

53.	A lever which always have mechanical advantage more than 1 is : (a) Lever of first order (b) Lever of second order (c) Lever of third order (d) none of these
Answer» (b) Lever of second order.

Discussion

54.	Which of the following statements is not true for a machine:(a) It always has efficiency less than 100%(b) its mechanical advantage can be less than 1.(c) It can also be used as a speed multiplier(d) It can have a mechanical advantage greater than the velocity ratio.
Answer» (d) It can have a mechanical advantage greater than the velocity ratio. Reason: If the mechanical advantage of a machine is greater than its velocity ratio, then it would mean that the efficiency of a machine is more than 100%, which is practically not possible.

54.

Which of the following statements is not true for a machine:(a) It always has efficiency less than 100%(b) its mechanical advantage can be less than 1.(c) It can also be used as a speed multiplier(d) It can have a mechanical advantage greater than the velocity ratio.

Answer»

(d) It can have a mechanical advantage greater than the velocity ratio.

Reason: If the mechanical advantage of a machine is greater than its velocity ratio, then it would mean that the efficiency of a machine is more than 100%, which is practically not possible.

Discussion

55.	Why does a lever of third order have a mechanical advantage less than 1?
Answer» M.A. of Illrd order lever is always less than 1 as effort arm is less than load arm M.A. = Effort arm/Load arm.

Discussion

56.	In which situation does the lever of first order have mechanical advantage (a) more than 1 (b) less than 1?
Answer» (a) Mechanical advantage can be more than 1 when effort arm is larger than load arm or by moving the fulcrum towards the load. (b) M.A. can be less than lwhen effort arm is smaller than load arm or by moving fulcrum towards effort.

56.

In which situation does the lever of first order have mechanical advantage (a) more than 1 (b) less than 1?

Answer»

(a) Mechanical advantage can be more than 1 when effort arm is larger than load arm or by moving the fulcrum towards the load.

(b) M.A. can be less than lwhen effort arm is smaller than load arm or by moving fulcrum towards effort.

Discussion

57.	Write a relationship between the mechanical advantage (M.A.) and velocity ratio (V.R.) of an ideal machine.
Answer» Efficiency = M.A/V.R in an ideal machine, ratio = 1 : 1 that means MA = VR.

57.

Write a relationship between the mechanical advantage (M.A.) and velocity ratio (V.R.) of an ideal machine.

Answer»

Efficiency = M.A/V.R

in an ideal machine, ratio = 1 : 1 that means MA = VR.

Discussion

58.	Write an expression to show the relationship between mechanical advantage, velocity ratio and efficiency for a simple machine.
Answer» Expression of relation M.A, V.R and efficiency is M.A. Efficiency η = M.A/V.R.

Discussion

59.	The lever for which the mechanical advantage is less than 1 has:(a) fulcrum at mid-point between load and effort.(b) Load between effort and fulcrum(c) effort between fulcrum and load(d) Load and effort acting at the same point
Answer» (c) effort is between fulcrum and load Hint: Levers, for which the mechanical advantage is less than 1, always have the effort arm shorter than the load arm.

59.

The lever for which the mechanical advantage is less than 1 has:(a) fulcrum at mid-point between load and effort.(b) Load between effort and fulcrum(c) effort between fulcrum and load(d) Load and effort acting at the same point

Answer»

(c) effort is between fulcrum and load

Hint: Levers, for which the mechanical advantage is less than 1, always have the effort arm shorter than the load arm.

Discussion

60.	A lever which can have mechanical advantage either less than one or more than one depending upon the position of fulcrum is a lever of : (a) First order (b) Second order (c) Third order (d) none of these
Answer» (a) First order.

Discussion

61.	The correct relationship between the effort (E) load (L) and mechanical advantage (M.A.) is : (a) M.A. = L × E (b) M.A. × E = L (c) M.A. x L= E (d) none of these
Answer» (b) M.A. × E = L

Discussion

62.	Class III levers have mechanical advantage less than one. Why are they then used?
Answer» With levers of class III, we do not get gain in force, but we get gain in speed, that is a longer displacement of load is obtained by a smaller displacement of effort.

Discussion

63.	A lever which always has mechanical advantage less than 1 has :(a) Load between effort and the fulcrum. (b) Effort between the load and the fulcrum. (c) Fulcrum between the load and effort. (d) Effort and load act at same point.
Answer» (b) Effort between the load and the fulcrum.

Discussion

64.	Which type of lever has a mechanical advantage always more than one? Give one example. What change can be made in this lever to increase its mechanical advantage?
Answer» Class II lever always have a mechanical advantage more than one. Example: a nut cracker. To increase its mechanical advantage we can increase the length of effort arm.

64.

Which type of lever has a mechanical advantage always more than one? Give one example. What change can be made in this lever to increase its mechanical advantage?

Answer»

Class II lever always have a mechanical advantage more than one.

Example: a nut cracker.

To increase its mechanical advantage we can increase the length of effort arm.

Discussion

65.	Define the term velocity ratio, state its unit.
Answer» The ratio of the velocity of effort to the velocity of the load is called the velocity ratio of machine. It has no unit.

Discussion

66.	What is the purpose of a jack in lifting a car by it?
Answer» The purpose of jack is to make the effort less than the load so that it works as a force multiplier.

Discussion

67.	Explain the term mechanical advantage. State its unit.
Answer» The ratio of the load to the effort is called mechanical advantage of the machine. It has no unit.

Discussion

68.	Define the following terms with reference to a machine (a) Total load (b) useful load (c) effort (d) ideal machine (e) ideal mechanical advantage (f) actual mechanical advantage (g) velocity ratio (h) efficiency.
Answer» (a) Total load : Load lifted by machine + resistance over come. (b) Useful load : “The load, a machine in able to lift.” (c) Effort : The effort applied by us on the machine. (d) Ideal machine : A machine whose parts are weightless and frictionless such that what so ever is the energy spent on it same is the energy produced by it, is called a perfect machine.” (e) Ideal mechanical advantage : “The ratio between total load moved (or resistance overcome) to the effort applied is called ideal mechanical advantage.” (f) Actual mechanical advantage : “The ratio between useful load moved to the effort applied is called actual mechanical advantage”. (g) Velocity ratio : [V.R.] : “Is the ratio of velocity of effort to velocity of load.” i. e “Ratio of effort arm to load arm.” (h) Efficiency : (η) “Efficiency of a machine is the ratio of useful work done by machine to the work put into the machine by the effort.”

68.

Define the following terms with reference to a machine (a) Total load (b) useful load (c) effort (d) ideal machine (e) ideal mechanical advantage (f) actual mechanical advantage (g) velocity ratio (h) efficiency.

Answer»

(a) Total load : Load lifted by machine + resistance over come.

(b) Useful load : “The load, a machine in able to lift.”

(c) Effort : The effort applied by us on the machine.

(d) Ideal machine : A machine whose parts are weightless and frictionless such that what so ever is the energy spent on it same is the energy produced by it, is called a perfect machine.”

(e) Ideal mechanical advantage : “The ratio between total load moved (or resistance overcome) to the effort applied is called ideal mechanical advantage.”

(f) Actual mechanical advantage : “The ratio between useful load moved to the effort applied is called actual mechanical advantage”.

(g) Velocity ratio : [V.R.] : “Is the ratio of velocity of effort to velocity of load.” i. e “Ratio of effort arm to load arm.”

(h) Efficiency : (η) “Efficiency of a machine is the ratio of useful work done by machine to the work put into the machine by the effort.”

Discussion

69.

What do you understand by an ideal machine? How does it differ from a practical machine?

Answer»

An ideal machine is a machine whose parts are weightless and frictionless so that which there is no dissipation of energy in any manner. Its efficiency is 100%, i.e. the work output is equal to work input.

Ideal machine	Practical machine
Efficiency is 100%.	Efficiency is less than 100%
Its parts are weightless, elastic and perfectly smooth.	Its parts are not weightless, elastic or perfectly smooth.
There is no loss in energy due to friction.	There is always some loss of energy due to friction.
Work output of such a machine is equal to the work input.	Work output is always less than the work input.

Discussion

70.	(i)Name six simple machines.(ii) Give one practical example of each machine named in (i)
Answer» (i) Simple machines are : 1. Lever 2. Pulley 3. Wedge 4. Inclined plane 5. Wheel and axle 6. Screw Example of : 1. Liver : is handle of common water pump helps in multiplying effort 2. Pulley : gears, used for changing the direction of the effort 3. Wedge : axe, A knife are the examples. 4. Inclined plane : Ramp or staircase or screw jack. 5. Wheel and axle : Free wheel or crank wheel of bicycle. 6. Screw : Screw bolt.

70.

(i)Name six simple machines.(ii) Give one practical example of each machine named in (i)

Answer»

(i) Simple machines are :

1. Lever

2. Pulley

3. Wedge

4. Inclined plane

5. Wheel and axle

6. Screw

Example of :

1. Liver : is handle of common water pump helps in multiplying effort

2. Pulley : gears, used for changing the direction of the effort

3. Wedge : axe, A knife are the examples.

4. Inclined plane : Ramp or staircase or screw jack.

5. Wheel and axle : Free wheel or crank wheel of bicycle.

6. Screw : Screw bolt.

Discussion

71.	State four ways in which machines are useful to us?
Answer» Machines are useful to us in the following ways: (1) In lifting a heavy load by applying a less effort. (2) In changing the point of application of effort to a convenient point. (3) In changing the direction of effort to a convenient direction. (4) For obtaining a gain in speed.

71.

State four ways in which machines are useful to us?

Answer»

Machines are useful to us in the following ways:

(1) In lifting a heavy load by applying a less effort.

(2) In changing the point of application of effort to a convenient point.

(3) In changing the direction of effort to a convenient direction.

(4) For obtaining a gain in speed.

Discussion

72.	Name six simple machines.
Answer» Simple machines are : 1. Lever 2. Pulley 3. Wedge 4. Inclined plane 5. Wheel and axle 6. Screw

72.

Name six simple machines.

Answer»

Simple machines are :

1. Lever

2. Pulley

3. Wedge

4. Inclined plane

5. Wheel and axle

6. Screw

Discussion

73.	(i) In what way does an ‘Ideal machine’ differ from a ‘Practical machine’? (ii) Can a simple machine act as a force multiplier and a speed multiplier at the same time?
Answer» (i) An ideal machine is the one whose parts are frictionless as well as weightless, such that its mechanical advantage is equal to its velocity ratio. A practical machine is the one whose parts are neither frictionless nor weightless. Furthermore, its mechanical advantage is always less than its velocity ratio. (ii) No, it can be either speed multiplier or force multiplier.

73.

(i) In what way does an ‘Ideal machine’ differ from a ‘Practical machine’? (ii) Can a simple machine act as a force multiplier and a speed multiplier at the same time?

Answer»

(i) An ideal machine is the one whose parts are frictionless as well as weightless, such that its mechanical advantage is equal to its velocity ratio.

A practical machine is the one whose parts are neither frictionless nor weightless. Furthermore, its mechanical advantage is always less than its velocity ratio.

(ii) No, it can be either speed multiplier or force multiplier.

Discussion

74.	State three functions of machine.
Answer» Functions of machines : 1. To act as force multiplier 2. To shift the point of application to a convenient place. 3. To multiply speed. 4. To change the direction of the force applied for greater ease and comfort.

74.

State three functions of machine.

Answer»

Functions of machines :

1. To act as force multiplier

2. To shift the point of application to a convenient place.

3. To multiply speed.

4. To change the direction of the force applied for greater ease and comfort.

Discussion

75.	What is a machine?
Answer» Machine : “Is a device which is used to transmit force to change the direction of force or to obtain speed.”

Discussion

Explore topic-wise InterviewSolutions in .

With reference to the terms Mechanical Advantage, Velocity Ratio and efficiency of a machine, name and define the term that will not change for machine of a given design.

With reference to the terms mechanical advantage, velocity ratio and efficiency of a machine, name the term that will not change for a machine of a given design.

A lever which always have mechanical advantage more than 1 is : (a) Lever of first order (b) Lever of second order (c) Lever of third order (d) none of these

Which of the following statements is not true for a machine:(a) It always has efficiency less than 100%(b) its mechanical advantage can be less than 1.(c) It can also be used as a speed multiplier(d) It can have a mechanical advantage greater than the velocity ratio.

Why does a lever of third order have a mechanical advantage less than 1?

In which situation does the lever of first order have mechanical advantage (a) more than 1 (b) less than 1?

Write a relationship between the mechanical advantage (M.A.) and velocity ratio (V.R.) of an ideal machine.

Write an expression to show the relationship between mechanical advantage, velocity ratio and efficiency for a simple machine.

The lever for which the mechanical advantage is less than 1 has:(a) fulcrum at mid-point between load and effort.(b) Load between effort and fulcrum(c) effort between fulcrum and load(d) Load and effort acting at the same point

A lever which can have mechanical advantage either less than one or more than one depending upon the position of fulcrum is a lever of : (a) First order (b) Second order (c) Third order (d) none of these

The correct relationship between the effort (E) load (L) and mechanical advantage (M.A.) is : (a) M.A. = L × E (b) M.A. × E = L (c) M.A. x L= E (d) none of these

Class III levers have mechanical advantage less than one. Why are they then used?

A lever which always has mechanical advantage less than 1 has :(a) Load between effort and the fulcrum. (b) Effort between the load and the fulcrum. (c) Fulcrum between the load and effort. (d) Effort and load act at same point.

Which type of lever has a mechanical advantage always more than one? Give one example. What change can be made in this lever to increase its mechanical advantage?

Define the term velocity ratio, state its unit.

What is the purpose of a jack in lifting a car by it?

Explain the term mechanical advantage. State its unit.

Define the following terms with reference to a machine (a) Total load (b) useful load (c) effort (d) ideal machine (e) ideal mechanical advantage (f) actual mechanical advantage (g) velocity ratio (h) efficiency.

What do you understand by an ideal machine? How does it differ from a practical machine?

(i)Name six simple machines.(ii) Give one practical example of each machine named in (i)

State four ways in which machines are useful to us?

Name six simple machines.

(i) In what way does an ‘Ideal machine’ differ from a ‘Practical machine’? (ii) Can a simple machine act as a force multiplier and a speed multiplier at the same time?

State three functions of machine.

What is a machine?