Simple Machines for Class 5
 |
| Simple Machines |
1. Choose the correct answer:
(i). A straight rod that can move around a fixed point on it is known as a
a. screw b. lever c. pulley d. wedge
(ii). A see-saw is an example of a
(iii). The small rod at the centre of a wheel is called a/an
(iv). A knife is an example of a
2. Write True or False for the following statements. Correct the False statements.
a. Two or more simple machines working together forms a complex machine.
Ans - True
b. A Washing machine is a simple machine.
c. A staircase is an example of a class 3 lever.
d. Ramps are used in hospitals to transport patients on wheel chair.
3. Fill in the blanks:
a. The __________ the fulcrum is to the load, the easier it is to do the work. (closer)
b. A machine helps us to do work with less __________. (effort)
c. The fixed point on a lever is called the ___________. (fulcrum)
d. In a class 2 lever, the __________ lies between the __________ and the __________. (load, fulcrum, effort)
e. Our elbow is an example of a class ______ lever. (3)
f. There are _______ types of simple machines. (6)
g. _____________ is the fixed point on a lever about which it is free to rotate. (Fulcrum)
h. In class 3 levers, the ____________ lies between the ____________ and the ____________. (effort, load, fulcrum)
i. A bicycle wheel is a ______________ type of simple machine. (wheel and axle)
j. A screw is a long nail with a spiral _____________ along its length. (thread)
k. An axe is an example of a ______________. (wedge)
4. What types of simple machines are the following:
a. Bottle opener - Class 2 lever
b. Nail cutter - Class 2 lever
c. Staircase - Inclined plane
d. Beam balance - Class 1 lever
5. What is force?
Force is a push or a pull.
6. What does force do?
The applied force changes the
a. direction of movement of the object
b. shape of the object and/or
c. speed of the object.
7. When is the work said to be done?
Work is said to be done, when force produces displacement.
8. What
is a machine? Why do we use machines?
A
machine is a device that makes work easier to do.
We use machines because they make our work easier and faster.
9. How many kinds of machines are there?
There are two kinds of machines. They are:
i. Simple Machines – They consist of few or no moving parts. Example, knife.
ii. Complex Machines – They consist of many moving parts. Example, washing machine, bicycle, etc.
10. What is a simple machine?
A simple machine is a machine that increases the size of the applied force or changes the direction of the applied force or does both. It is made up of only a few parts.
11. Name
the following:
i. Six kinds of Simple Machines –
· lever
· inclined
plane
· wedge
· screw
· wheel
& axle and
· pulley.
ii. Any four Complex Machines –
· bicycle
· wheel
barrow
· crane
and
· car.
12. What
is a complex machine?
Complex machine is a machine
that is made up of a large number of simple machines.
13. What
is a lever?
A rigid bar free to turn
about a fixed point is called a lever.
14. What
is a fulcrum?
The fixed point about which
a lever turns freely, is called fulcrum.
15. What
is load?
The object to be moved is called
the load or resistance.
16. What
is effort?
The force applied to move an
object is called the effort or power.
17. Define
load arm.
The distance from the fulcrum
to the Load is called the load arm.
18. Define
effort arm.
The distance from the fulcrum to the point of application of effort is called the effort arm or the power arm.
19. How
is a lever balanced?
A
lever is balanced by changing the position of the load and effort
20. State
the principle of lever.
The principle of lever is:
load x load arm = effort x effort arm
21. How can we increase the load to be lifted?
We can increase the load to be lifted by increasing the effort arm.
22. Explain the different classes of lever. Give examples.
There are three classes of lever:
- Lever of class I - the fulcrum lies in between the effort and the load. Example see-saw, a pair of scissors, plier, oars of a boat, beam balance, etc.
- Lever of class II - the load lies in between the fulcrum and the effort. Example, wheel-barrow, nutcracker, bottle opener, nail cutter, lemon squeezer, etc.
- Lever of class III - the effort lies in between the fulcrum and the load. It increases the speed at which a load is moved. Example, forceps, a pair of tongs, fishing rod, hockey stick, cricket bat, badminton racquet, tennis racquet, hand held paper fan, broom, pair of tweezers, our elbow, etc.
23. What is an inclined plane?
An inclined plane is a
machine used to raise or lower a heavy load with a relatively small force. It is a plane at an angle, such that its one end is higher than the other. For example, staircase, ramps in hospitals.
24. How does
an inclined plane reduce our work?
An inclined plane reduces
our work by multiplying the force applied for raising the load.
25.
What are the uses of inclined plane?
An inclined plane is used for loading and unloading heavy things which can be rolled.
26.
What is a screw?
A screw is a combination of an inclined plane and a circle. It is a long nail with a spiral metal thread along its length.
27. How does a screw help us?
We use screws to join two pieces of wood together. It holds the pieces together more firmly than a nail.
28. What are the uses of screw?
A screw is used to hold things together.
29.
What is thread of screw?
The spiral ridges of a screw are called the thread of a screw.
30.
What is pitch of a screw?
The distance between two threads of a screw is called a pitch.
31.
What is wedge?
A wedge is a combination of two inclined planes, put back to back. These inclined planes give the wedge its sharp edge to split things apart. Example, axe, knife, etc.
32.
What are the uses of wedge?
A wedge is used to split and cut things.
33. How does a wedge act as a simple machine?
A wedge is a simple machine, as it consists of very few parts - two inclined planes, put back to back. These inclined planes give the wedge its sharp edge to split things apart.
34.
Explain wheel and axle arrangement.
A wheel is like a roller to reduce the friction. An axle itself is a form of a wheel. Therefore, wheel and axle consists of a big cylinder joined to a small cylinder. The big cylinder is called the wheel and the small cylinder is called the axle. The wheel turns the axle.
35.
What are the uses of wheel and axle arrangement?
A wheel and axle arrangement is used to lift heavy loads.
36.
What is a pulley?
A pulley is a flat circular disc with a groove along its rim for a string to pass over and is mounted on a rigid support.
37.
What are the uses of pulley?
A pulley is used to lift a load straight up.
38.
How does a pulley make our work easier?
A pulley makes our work easier by changing the direction of the force applied.
39.
What is a fixed pulley?
A pulley in which a grooved wheel is fixed to a support high up and a rope goes round the wheel is called a single fixed pulley. The load is fixed to one end of the rope and the effort is applied downwards at the other end of the rope.
40.
What are the uses of single fixed pulley?
The single fixed pulley is used to:
Ø hoist a flag.
Ø draw water from a well.
Ø lift heavy load in factories or on construction sites.
41.
How is a wheel a simple machine?
A wheel is often used much like a roller to reduce the friction. When a wheel is used with an axle, it is considered a simple machine. It has very few parts in it.
42.
What is the advantage of a single fixed
pulley?
The effort moves much more than the load when more wheels are used. So, less effort is used.
43. Explain wheel and axle arrangement.
The wheel and axle arrangement consists of a wheel fixed to an axle. This makes the wheel and axle move together.
44. What is a screw-jack?
A jack used by mechanics on the principle of screw is called a screw-jack.
45. What is a car jack?
A car jack is used to lift cars, so that we can work on the underside of a car.
46. What is the role of a screw in a car jack?
A car jack is operated by turning a screw, called the jackscrew.
47. Describe
an experiment to show how wheels help to move objects.
Let us put an almirah full
of books on a rough surface. We will find that it is very
difficult to push the almirah as it is.
Let us now put some
cylindrical rods under the almirah. We will find that
now it is easier to push the almirah.
Let us now replace the
cylindrical rods by wheels. We will find that now it becomes even more easy to
the almirah.
This is how wheel helps to
move objects.
48. Which
are the most common machines used in school?
The
most common machines used in school are pen, eraser, etc.
49. What are some common simple machines used at home?
The most common machines used at home are nail cutter, scissor, plier, a screw top jar lid, door knob, can opener, wheel in a chair, a door stop, etc.
50. What are examples of some common complex machines?
The most common complex machines are bicycle, car-jack, wheel-barrow, lawn-mower, etc.
51. How does a bicycle work?
In a bicycle, each wheel is attached to an axle at the center. when we push the pedals with our feet, the axles turn and wheels also move along with them.
52. Why
is oiling of some parts of machines necessary?
Moving parts of machines
suffer a lot of wear and tear. They also start making harsh sound. Such parts
should be lubricated regularly to reduce friction between these moving parts.
53. How is
a machine taken care of in the following:
i. The axle
of pulley fixed on a well may not wear out
To prevent wearing out of moving parts, they should be lubricated regularly.
ii. The handle
of a bicycle may not rust
To protect the outer parts
of a machine from rusting, they should be painted.
iii. Delicate
machines of the factory may not be spoiled due to wear and tear
Delicate parts of a machine should
be lubricated regularly and it should be properly covered when not in use.
Comments