Machines Class-10 Goyal Brothers  ICSE Physics Solutions Chapter-3 Machines . We Provide Step by Step Answer of Exercise, MCQs, Numericals Practice Problem Questions of Exercise-1 Machines ICSE Class-10 . Visit official Website CISCE  for detail information about ICSE Board Class-10 Physics.

## Machines Class-10 Goyal Brothers ICSE Physics Solutions Ch-3

-: Select Topics :-

Exercise-1

MCQ -1

Numericals Practice Problems-1

Exercise-2

MCQ -2

Numericals Practice Problems-2

### Exe-1 Machines Class-10 Goyal Brothers ICSE Physics Solutions Ch-3

Page-37,38

Question 1.
(a) What is a machine ?
(b) State three functions of machine.
(a) Machine : “Is a device which is used to transmit force to change the direction of force or to obtain speed.”
(b) 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.

Question 2.

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

(a) Simple machines are :

1. Lever
2. Pulley
3. Wedge
4. Inclined plane
5. Wheel and axle
6. Screw

(b) 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.

Question 3.
Define the following terms with reference to a machine

(c) effort
(d) ideal machine
(g) velocity ratio
(h) efficiency

(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.”

Question 4.
Prove that efficiency of a machine is the ratio between mechanical advantage and velocity ratio.
Relation Between M.A., V.R And Efficiency :

Question 5.
Give two reasons, why machine cannot be 100% efficient.

1. Apart of input is always used in moving the parts of machine.
2. A part of input is wasted in overcoming friction between various parts of machine.

Question 6.
(a) Define lever. What are its kinds ?
(b) How will you determine the order of a lever ?
(a) Lever : “Is a straight or bent rigid rod which can turn about a fixed point called fulcrum”
(b) Out of effort (E), Load (L) and Fulcrum (F), the one which is in between the other two determines the order of lever i.e.
If F is in between L and E, then it is lever of 1 st order
If L is in between F and E. It is of second order lever.
If E is in between L and F, it is Illrd order lever.

Question 7.
To which order do the following levers belong and why ?

(a) A railway signal
(b) A man cutting bread with a knife
(c) A boy writing a piece of paper
(d) A nut cracker
(e) handle of a water pump
(f) see-saw
(g) forceps
(h) A man rowing a boat
(i) A lock and key
(j) Soda water opener
(k) a door
(l) motorcarfoot brake
(m) fishing rod
(n) lemon squeezer.

(a) A railway signals – Lever of 1st order as F is in between load and effort
(b) Cutting a bread with knife is third order lever as effort is in between load and fulcrum.

(c) A boy writing a piece of paper is Illrd order lever as effort is in between load and fulcrum.
(d) A nut cracker is II nd order lever as load is in between effort and fulcrum.

(e) Handle of water pump : 1st order lever as fulcrum is in between effort and load

(f) See-saw : Lever of 1st order as fulcrum is in between load and effort

(g) Forceps : Illrd order lever as effort is in between fulcrum and load.

(h) A man rowing a boat : End order of lever as load is in between effort and fulcrum

(i) Bottle Opener : Ilnd order lever as load is in between fulcrum and effort.

(j) Soda – water opener : 2nd order lever as load is in between fulcrum and effort.
(k) A door : Ilnd order lever as load is in between effort and fulcrum.
(l) Motorcar foot brake : 3 rd order lever as effort is in between load and fulcrum.

(m) A fishing rod : 3 rd order lever as effort is in between fulcrum and load.
(n) Lemon squeezer : 2 nd class lever as load is in between fulcrum and effort.

Question 8.
Why does a lever of second order have mechanical advantage more than one ?
M.A. of second order of lever is more than one as effort arm is longer than load arm M.A = Effort arm / Load arm

Question 9.
Why does a lever of third order have a mechanical advantage less than 1 ?
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

Question 10.
In which situation does the lever of first order have mechanical advantage (a) more than 1 (b) less than 1 ?

(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.

Question 11.
Why are cutting edges of pliers smaller than the cutting edges of scissors ?
Cutting edges of pliers are smaller to make it force multiplier. Load arm is kept very small because the resistance (load) of the metal is very large and to over come this resistance the effort arm is made larger.

### Multiple Choice Questions-1

Machines Class-10 Goyal Brothers  ICSE Physics Solutions

1. Which of the statement is not true for a machine ?
(a) It can multiply force
(b) It can increase speed
(c) It can change the direction of applied force.
(d) Its output can be more than input.
(d) Its output can be more than input.

2. Which of the statement is not true for an actual machine?
(a) Its mechanical advantage is less than velocity ratio.
(b) Its efficiency is always less than 100%
(c) Its mechanical advantage is greater than velocity ratio.
(d) Output of machine is always less than input.
(c) Its mechanical advantage is greater than velocity ratio.

3. 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.
(b) Effort between the load and the fulcrum.

4. 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
(b) M.A. × E = L

5. The correct relationship between the velocity ratio (V.R) the distance through which effort act (d) and the distance through which load moves (D)
(a) V.R. × D = d
(b) V.R. = D × d
(c) V.R. × d = D
(d) none of these
(a) V.R. × D = d

6. The correct relationship between the efficiency (η), mechanical advantage (M.A.) and velocity ratio (V.R.) of an actual machine is :
(a) η = M.A × V.R
(b) η = M.A. ÷ V.R.
(c) η × V.R. = M.A.
(d) both (b) and (c)
(c) η × V.R. = M.A.

7. A fire tong is a lever of :
(a) First order
(b) Second order
(c) Third order
(d) none of these
(c) Third order

8. A person standing vertically upon his toes is an example of lever of :
(a) First order
(b) Second order
(c) Third order
(d) none of these
(c) Third order

9. 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
(b) Lever of second order

10. 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
(a) First order

### Numerical Problems on Machine-1

Machines Class-10 Goyal Brothers  ICSE Physics Solutions

Page-39,40,41

Practice Problems 1

Question 1.
In operating a water pump, a resistance of 480 N is overcome by an effort of 72 N. If the distance of the fulcrum from the point where the resistance act is 0.2 m. Find the distance from the fulcrum where effort is applied.

Question 2.
A uniform plank of a see-saw is 5m long and supported at its centre. A boy weighing 40 kgf sits at a distance 1.5 m from one end of the see-saw where must a girl weighing 25 kgf sit on the other end of the see-saw so as to balance the boy ?

Practice Problems 2

Question 1.
The handle of a nutcracker is 16 cm long and a nut is placed 2 cm from its hinge. If a force of 4 kgf is applied at the end of the handle to crack it, what weight, if simply, placed on the nut will crack it ?

Question 2.
An effort of 50 kgf is applied at the end of a lever of the second order, which supports a load of 750 kgf, such that the load is at a distance of 0.1 m from the hinge. Find the length of the lever. (Assume that the lever is weightless)

Practice Problems 3

Question 1.
A machine displaces a load of 125 kgf through a distance 0. 30 m, when an effort of 12.5 kgf acts through a distance of 4.0 m. Calculate the

(a) velocity ratio
(c) % age efficiency of the machine.

Question 2.
Calculate the (a) velocity ratio (b) mechanical advantage (c) %age efficiency of a machine which overcomes a resistance of 800 N through a distance of 0.12 m, when an effort of 160 N acts through a distance of 0.72 m.

Practice Problems 4

Question 1.
An effort of 500 N is applied through a distance of 0.50 m on a machine, whose efficiency is 90% such that resistance is overcome through a distance of 0.04 nuCalculate the (a) V.R. (b) M.A. (c) resistance overcome by the machine.

Question 2.
A crow-bar of length 2.0 m is used as a machine, to lift a box of 100 kgf by placing a fulcrum at a distance of 0.1 m from the box Calculate the (a) V.R (b) effort required. What assumption has been made by you in solving the problem ?

Practice Problems 5

Question 1.
The handle of a water pump is 90 cm long from its piston rod. If the pivot of handle is at a distance of 15 cm from the piston rod, calculate :
(b) least effort required at its other end to overcome a resistance of 60 kgf.

Question 2.
A crowbar of length 2.5 m is pivoted at a point 25 cm from its tip. Calculate (i) mechanical advantage of crowbar (ii) the maximum load displaced by it by applying an effort of 100 kgf on its extreme end.

Practice Problems 6

Question 1.
A walnut can be broken by applying a direct force of 50 kgf. If the walnut is placed in a nut crackers, the length of whose handle is 18 cm and nut is placed 2 cm from the pivot, calculate the minimum force required to crack the nut.

Question 2.
A key is 5 cm long the turns the levers of a lock at a distance 1 cm. If the lock is opened by an effort of 10 N, calculate the resistance offered by the levers of the lock.

Practice Problems 7

Question 1.
A door is 1 m wide. It can be closed by an effort of 25 N, when effort is applied at a distance of 0.4 m from the hinge. What effort is needed, if it is applied at its extreme end ?
E × Effort arm
25 N × 0.4 m
∵ work done in both cases is same
Now effort EN × 1 m = 10
E= 10/1 = 10N

Question 2.
A nut can be opened by a lever of length 0.25 m by applying a force of 80 N. What should be the length of lever, if a force of 32 N is enough to open the nut ?

### Exe-2 Machines Class-10 Goyal Brothers  ICSE Physics Solutions Ch-3

Page-44

Question 1.
What is a pulley ?
Pulley : “is a flat circular disc, having a groove in its edge and capable of rotating about a fixed point passing through its centre commonly called axle.”

Question 2.
Mechanical advantage of a single fixed pulley is always less than 1. Why is the pulley commonly used ?
The effort can be applied in a more convenient direction with the single fixed pulley.
One can conveniently make use of his own weight also for the effort.

Question 3.
Draw a diagram of a single movable pulley system. Why is this system preferred to a single fixed pulley system ?
Single movable pulley : The single movable pulley is preferred to a single fixed pulley because load can be lifted by applying an effort equal to half the load (in ideal situation) i.e. the pulley acts as a force multiplier.

Question 4.
Draw diagram of pulley system having velocity ratio (a) six (b) three
(a) Six pulleys L = 6T

Velocity Ratio (V.R.) : In a system of n pulley if the load moves up through a distance d, the effort end moves through a distance because each segment of the string supporting the load is loosened by a length d i.e. dL = d then dE = nd
∴ Velocity ratio = nd/d = n
Thus the V.R. is always equal to the number of strands of tackle (or section of the string) supporting the load.

Question 5.
How can a single pulley be used as a single movable pulley ? Explain or draw a labelled diagram.
Single movable pulley : “A pulley whose axis of rotation-is movable (not fixed in position) is a movable pulley done in Q.3.

### Multiple Choice Questions-2

Machines Class-10 Goyal Brothers  ICSE Physics Solutions

1. A single fixed pulley is used because :
(a) its efficiency is 100%
(b) it multiplies effort
(c) it multiplies speed
(d) it changes the direction of applied effort
(d) it changes the direction of applied effort

2. The actual mechanical advantage of a single movable pulley is :
(a) one
(b) two
(c) less than 2, but more than 1
(d) none of these
(c) less than 2, but more than 1

3. A sheaf pulley system has :
(a) efficiency more than 100%
(b) multiplies speed
(c) multiplies effort
(d) both (a) and (b)
(c) multiplies effort

4. A pulley system has 5 pulley in all. Its velocity ratio is :
(a) 5
(b) less than 5
(c) more than 5
(d) none of these
(a) 5

5. A single movable pulley has :
(a) velocity ratio 2, and actual mechanical advantage 2
(b) velocity ratio 2, and actual mechanical advantage less than 2
(c) velocity ratio 2, and actual mechanical advantage more than 2
(d) none of the above
(b) velocity ratio 2, and actual mechanical advantage less than 2

6. An actual pulley system always has mechanical advantage less than velocity ratio. It is because :
(a) a part of effort is wasted in overcoming friction.
(b) a part of effort is wasted in overcoming load of movable block
(c) both (a) and (b)
(d) none of these
(c) both (a) and (b)

### Numerical Problems on Machine -2

Machines Class-10 Goyal Brothers  ICSE Physics Solutions

Page-45,46,47

Practice Problems 1

Question 1.
A pulley system has five pulley in all and is 90% efficient. Calculate

(b) the effort required to lift a load of1000 N
(c) the resistance due to the movable parts of the machine and friction.

Question 2.      Machines Class-10 Goyal Brothers
Diagram shows a single movable pulley system.

(a) Mark the direction of force due to tension.
(b) What is the purpose of the fixed pulley ?
(c) If T is the tension in newtons, what is the relation between T and E ?
(d) Calculate VR of the system.
(e) Assuming efficiency is 100%, what is the mechanical advantage ?
(f) Calculate the effort E.

(a) Force due to tension is shown.

(b) Purpose of fixed pulley:
(i) If effort is applied only in upward direction it is inconvenient. With the single fixed pulley B to change the direction of force is shown.
(ii) More over one can use his own weight also at effort as it will be quite convenient.
(c) T = E
(d) V.R = distance moved by effort / distance moved by load
V.R. = 2d/d = 2
∵ When free end of string is pulled up by the effort through 2d, then load is raised up through a distance d.
(e) M.A. / V.R. = η

Practice Problems 2

Question 1.
Diagram alongside show a pulley system when a load of 30 kgf is attached to a movable block.

(a) What is the velocity ratio of pulley system ?
(b) What is the mechanical adyantage of pulley system assuming it is ideal ?
(c) What is the magnitude of effort applied ?
(d) If the pulley system is not ideal and is 60% efficient, what is the effort required ?

L = 3 kgf
If free end of string is pulled up by the effort through 3d, then the load is raised up through a distance d

Question 2.
A pulley system has five pulleys in all, 2 in the movable block and three in fixed block, such that effort is applied in the upward direction and a load of 60 kgf is attached to the movable block.

(a) What is the velocity ratio of pulley system ?
(b) Assuming pulley system an ideal one, what is the mechanical advantage ?
(c) What is the magnitude of effort applied ?
(d) If the pulley system is not ideal but is 75% efficient, what is the effort required ?

Practice Problems 3

Question 1.      Machines Class-10 Goyal Brothers
A pulley system with velocity ratio 4 is used to lift a load of 100 kgf through a vertical height of IS m. The effort required to do so is 40 kgf which is applied in the downward direction. Calculate :

(a) Distance through which effort is applied
(b) Work done by the effort
(c) Mechanical advantage of pulley system
(d) Efficiency of pulley system.
(e) Number of pulleys in the upper and lower block. [Take g = 10 N kg-1]

Question 2.
A pulley system with velocity ratio 3 is used to lift a load of 60 kgf through a height of 20 m. The force is applied in upward direction and its magnitude is 25 kgf. Calculate :

(a) Distance through which effort is applied
(b) Work done by the effort
(c) Mechanical advantage of pulley system
(d) Efficiency of pulley system
(e) Total number of pulleys in the fixed and movable block. [Take g = 10 N kg-1]

V.R. = 3

-: End of Machine : Goyal Brothers  ICSE Physics Class-10 Solution :-