10 – Force and Types of Force
Q 1. Choose
the term to fill in the blanks :
1)
…………….has to be applied to change the……….. of a………….object.
(moving
direction force)
2) When an elephant drags a wooden log over
the land, the forces that are applied
on the log are ……………., ………………, and ……………….
(muscular
force, mechanical force, gravitational force, frictional force)
3) A
ball was set rolling on a large table. If it's ………… is to be changed, a …………will
have be applied on it (force, motion, gravitation)
4) The
force of friction always acts......... the motion. (along, against)
Ans
1)
Force has to be applied to change the direction of a moving object.
2)
When an elephant drags a wooden log over the land, the forces that are applied on the log are muscular
force, gravitational force and frictional force.
3) A
ball was set rolling on a large table. If it's, motion is to be changed, a
force will have to be applied on it.
4) The
force of friction always acts against the motion
Q 2. Match the following
Group A Group B (Ans)
1. An ox
pulling a cart - Muscular force
2. Lifting
a heavy iron object with a crane - Magnetic force
3.
Weighing with a spring balance - Gravitational force
4.
Applying brakes to a bicycle - frictional
force
5.
Picking up pieces of paper with a plastie scale - Electrostatic force.
Q. 3. One or more forces are acting in
the following examples. Name them.
1) An object fitting from a tall building.
Ans.
Gravitational force
2) An
aeroplane flying in the sky
Ans. Mechanical force, muscular force,
frictional force, gravitational force.
3)
Squeezing sugarcane juice with a squeezer.
Ans.
Mechanical force, muscular force, frictional force.
4)
Winnowing food grains.
Ans.
Muscular force gravitational force.
Q. 4. Explain in your own words giving
one example each:
(1)
Muscular force :
Ans.
The bones and muscles of our body help us to perform movements. Muscular force
is used to perform all these movements. The force applied with the help of
muscles is called muscular force e.g. a man who pulls the handcart uses
muscular force to perform the work. The coolie lifting the luggage uses
muscular force.
(2)
Gravitational force:
Ans.
Earth pulls all the objects towards it. This force is called gravitational
force or gravity. E.g. The rocket that takes off from the ground, applies the
mechanical force against the gravitational force. All the things on the earth,
stay on the earth due to gravitational force.
(3)
Mechanical force
Ans.
The force applied with the help of machine is called mechanical force. some
machines are used with the help of a muscular force, while some machines work
on electricity or fuel.these machines are automatic. Machines help us to carry
out tasks with ease and speed.
e.g.
washing machine, food processor, water pump
(4)
Electrostatic force
Ans.
Electrostatic force is produced by the materials which develop static
electricity on them. E.g.due to electrically charged materials like ebonite
plastic, rubber this force is
produced
(5)
The force of friction / Frictional force
Ans.
Frictional force is created by friction. Two surfaces rub against each other
and produce frictional force. E.g. the brakes used in stopping a running
vehicle work on the frictional force. The footpaths and slopes of the walk ways
have rough surface to create more frictional force, so that people do not slip
and fall as they walk.
(6)
Magnetic force :
Ans.
The force exerted by a magnet is called magnetic force. Magnetic force is used
in
Many
gadgets such as doorbell, huge cranes that lift loads.
Q 5.
Why? (Give reasons) :
1.
Machines
are oiled from time to time.
Ans Machines
are used to save our energy and time. The machines working mechanical force should work efficiently. If they are
not oiled, the frictional force may be created between the surfaces of this
machine. If frictional force is more it will slow down and speed
and
efficiency of the machine, therefore, machines are oiled from time to time
2.
An
object thrown upwards comes down after reaching a point.
Ans .
An object thrown upwards goes up due to muscular force. At one point during its
ascent
the muscular force becomes zero. The gravitational force then starts operating on
this object. It pulls this object down. Thus, an object thrown upwards comes
down after reaching a point.
(3) Powder is sprinkled on a carrom board.
Ans.
The coins on the carrom board should move swiftly during play. If powder is not
sprinkled on the surface of the carrom board, there would be more frictional force
This will hinder the play. Therefore, to have a smooth carrom board surface, powder
is sprinkled on a carrom board.
(4)
The ramp at a railway station has a rough surface.
Ans.
There should be more frictional force created on the ramp of the railway
station.if the surface is smooth and
slippery, there will be no frictional force. People using ramp in
a
hurry will slip and fall down easily. In order to avoid this and keep people
safe, the ramp at a railway station has a rough surface.
Q. 6. In what way are we different
(1) Muscular force and mechanical force
Ans. Muscular force Mechanical
force
1.
Muscular
force is created by our
1. Mechanical force is created by the
muscles i.e. in our body
machines.
2.
Muscular force is created due to the 2. Mechanical force is created
due to
energy created by the food we eat. electricity or
(2) The Force of friction and
Gravitational force :
Ans The Force of
friction
Gravitational force
1.
The
force of friction is created between (1) Gravitational force is created
by
two rough surfaces
the earth's surface and it acts on
every object
present on the earth.
2.
The frictional force always acts against (2) The motion of an object goes
on the direction of motion. increasing
with an increase in
gravitational
force.
3.
The force of friction can be increased (3) The gravitational force cannot
be
or decreased
Increased or decreased.
Q. 7. Write answers to the following
questions in your own words:
(1)
What are the things that can be done by applying force ?
Ans.
Force can be applied to almost all things. Lifting, pulling, riding a bicycle, pushing
a load, squeezing or bending something, driving vehicles, using different
machine and almost all the day-to-day activities are done by applying force.
(2) What is meant by weight?
Ans. The gravitational force acting on an
object is called the weight of that object
(3) Which machines run on muscular
force ?
Ans.
Handcart. plough, ores of boat, bullock cart. horse carriage. bicycle, grinding
stone, etc. are the machines that run on muscular force.
(4)
Which forces are acting upon an aeroplane taking off into the sky ?
Ans.
When an aeroplane takes off, it uses mechanical force. The pilot uses muscular
force. The weight or gravitational force pulls down the aeroplane. This opposes
the lift created by air flowing over the wing. This is a frictional force.
Thrust is generated by propeller, this is a mechanical force and opposes drag
caused by air resistance to the airplane.
(3) Solve the following crossword puzzle :(
Answers are given directly)
Down:
Ans.
1______ force is to be applied to push
a
scooter that has failed.
(2) ___________ force can be used to pick up
scattered pins.
Across
:
(1) A
..... pulls an iron nail towards itsell
(3)
------------- force was used when the farm was ploughed with a tractor.
(4) It
is due to the force of ........... that raindrops fall to the ground.
