MACHINES: PHYSICS (CLASS 6)

LEVERS

Lever: A lever is a rigid body capable of rotating about a point on itself.

You need to know F,L , E- FROG LAYS EGGS

F Fulcrum:  The fulcrum of a lever is the point about which it can rorate.
L load:  The resistance overcome by a lever is called load.
E Effort: The force applied to a lever is called the effort.

LEVERS ARE GROUPED INTO THREE CLASSES OR TYPES:

1^st  class lever- when the fulcrum is in the middle.

2^nd class lever- when the load is in the middle.

3 rd class lever- when the effort is in the middle.

ALGEBRA (CLASS 6)

DIVISION:

EXERCISE 13 (E)   PAGE NO. 127

(I)            DIVISION OF A MONOMIAL BY A MONOMIAL:

1.  DIVIDE

i.3a  by a

 =3 x a / a (cancel the terms)

=3         (/ MEANS DIVISION SIGN)

v. 30p² by 10p²

=30 x p x p/10 x p x p(cancel)

=3

viii 100by 50b

= 100\50xb

=20/b

(Do other sums)

2.Simplify

iv. -24a²b²c² by 6ab

= -24 x a x a x b x b x c x c\ 6 a x b (cancel)

=-4a x b x c²

=-4abc²

vi. 40p³q⁴r⁵ by 10p³q

=40xp x p x p x q x q x q x q x r x r x r x r x r /  10 p x p x p x q

=4q³r⁵

Taking these as examples do others sums

3.DIVIDE

i. -3m/4 by 2 m

=-3 x m/4 x ½ m(division )

=-3/8

iii.-21m⁵ n⁷ by 14 m²n²

=-21x m x m x m x m x m x n x n x n x n x n x n x n/ 14 x m x m x n x n

=-3 x m x m x m x n x n x n x n x n x n/2

=-3m³n⁵/2

viii -5.5x²/y by 11 x /y OBSERVE THE STEPS CAREFULLY

=-5.5X x X x /y  X y/11x

=-0.5 x

Do  other sums

4.SIMPLIFY

i. -15 m⁵ n² / -3 m⁵

SOLUTION:

=5 n²( cancel the signs  as well the terms)

(II)          DIVISION OF A POLYNOMIAL BY A MONOMIAL:

5.DIVIDE

i. 9x³-6 x² by 3 x

SOLUTION

=this means 9 x ³/ 3 x – 6 x² /3 x

=9.x.x.x/3.x – 6.x.x /3.x  (. Means multiply)

=3.x.x-2.x

=3x²- 2x

iii.15x³y² +25x²y³-36x⁴y⁴  by 5x²y²

SOLUTION:

=15.x.x.x.y.y.y \ 5x.x.y.y +  25.x.x.y.y.y /5.x.x.y.y- 36.x.x.x.x.x .y.y.y.y /5x.x .y.y

=3.x .y +5.y -36/5.x.x.y.y (after cancelling)

=3xy+ 5y- 36/5 x²y²

DEAR STUDENTS DO EXPECTED SUMS VERY SERIOUSLY.

MACHINES (CLASS 6)

FUNCTION OF MACHINES:

Machines can perform a number of functions, such as 

a. Changing the point of application of a force
b. Changing the direction in which force is applied
c.Changing the magnitude of the force
d. Changing the speed of the point of application of a force

TYPES OF MACHINES:

1.Lever
2.Inclined plane
3.Wedge
4.Screw
5.Wheel and Axle

will be continued.....

AIR AND WATER (CLASS 5)

 AIR AND WATER

4 a. Name the gases present in air.
Ans. The gases present in air Nitrogen,Oxygen, Carbon dioxide and Water vapors .


b.How does atmosphere help us?
Ans. Atmosphere helps in following ways: It protects the earth from becoming too hot by stopping the harmful sun’s rays.It also helps in escaping the heat from the earth.

c.How is air pressure used in our daily lives?

Ans.We use air pressure to drink juice from a straw, filling the ink inside a pen and also to Tyre to support vehicles and aircraft.

d.How are soluble impurities removed from water?
Ans. Soluble impurities are removed by the processes evaporation and distillation.


e.How water is made safe for drinking before being supplied to our house?
Ans. Water is treated by sedimentation, filtration, and chlorination before it reaches our house.

Dear students do Questions: 1, 2, and 3. 

PERCENTAGE (CLASS 6)

PERCENTAGE:  EXERCISE 9(C)

THIS EXERCISE IS BASED UPON SIMPLE APPLICATION OF THE FORMULAS THAT IS

INCREASE%  AND DECREASE%.

Increase %=Increase in value/Original value x 100 %       ...............(i)

Decrease %=Decrease in value/Original value x 100 %    …………(ii)

1.The price of rice rises from Rs 30 per kg to Rs 36.Find the percentage rise in the price of rice.

The price of the rice increases from Rs 30 to Rs 36

Increase in price =Rs 36 – Rs 30  =Rs 6

Increase %= Increase in value / original value  x 100 %

                 =Rs 6 /Rs 30 x 100 % [ cancel]

                =20% (Ans.)

2.The population of a small locality was 4000 in 1979 and became 4500 in 1981 .By what percent did the population increase?

Do this sum using the above steps

3. The price of the scooter was Rs 8000 from in 1975 .It reduced to Rs 6000 in 1980. By what

percent did the price of the scooter reduce?

The price of the scooter decreased from RS 8000 TO RS 6000.

Decreased in price = RS 8000- RS 6000 = RS 2000

Decrease%= decrease in value / original value x 100%

                   =RS 2000 / RS 8000 X 100%          
                   =25%

                     

4.Find the resulting quantity when:

i Rs 400 is decreased by 8 %

  = 8 % of RS 400

   = 8/100 x RS 400

=    RS 32

 DECREASED IN PRICE = RS 400 – RS 32

                                       =RS 368

ii 25 KM IS INCREASED BY 5 %

=  5% of 25 KM

= 5/ 100% X 25 KM

=1.25 KM

INCREASED  IN PRICE = 25KM + 1.25KM

                                         =26.25 KM

 Do (iii) and (iv) using above steps

5.THE POPULATION OF A VILLAGe  IS DECREASED BY 12 % .  IF THE ORIGINAL POPULATION WAS 25,000, FIND  THE POPULATION  AFTER  DECREASE?

POPULATION DECREASED = 12 % OF 25000

                                          

FOLLOW THE STEPS OF QUES 4 NO (I)

AIR AND WATER ( CLASS 5)

CHAPTER 11: AIR AND WATER

AIR

Air a mixture of different gases. Nitrogen and oxygen are mostly found in nature.

Gases present in the air

Air contains oxygen, carbon dioxide, nitrogen, dust , water vapour, smoke and germs.

 ATMOSPHERE

Our earth is covered by a layer like a blanket which protect us is called atmosphere.

 Atmosphere helps in following ways.

1.    It protects the earth from becoming too hot by stopping the harmful sun’s rays.

2.    It also helps in escaping the heat from the earth.

 Properties of air

Air occupies space, has weight and exerts pressure.

Air pressure

As we know, the air in the atmosphere is made up of a number of gases. These gases press down on the Earth’s surface, exerting a force that we call atmospheric pressure or air pressure. Although we are usually unaware of this pressure, it actually presses down very hard – roughly equivalent to the force of an elephant balancing on a desk!

Uses of air pressure in our daily life.

1.      We use air pressure to drink juice from a straw.

2.      While filling the ink inside a pen.

WATER

Water is the most important liquid on Earth.  All plants and animals need water to live.

Water cover almost 75% of Earth’s surface in the form of oceans, rivers, and lakes but very little of this water is fit for use.

Water impurities.

Any substances that makes the water dirty is the water impurities.

Two kinds of impurities -

Soluble impurities- which are soluble in water --- salt ,

Insoluble  impurities – which are in soluble in water –mud, oil.

REMOVING SOLUBLE IMPURITIES

EVAPORATION- changing of water into vapour on heating.

DISTILLATION- is a process of getting pure water by evaporation and condensation.

REMOVING INSOLUBLE IMPURITIES

1.      Sedimentation-EXPERIMENT FOR YOU

Take a platic bottle, fill sand and water to it shake the bottle and leave it for some time ,you will find

The sediments have settled.

2.      Decantation

Without disturbing the water pour the water in to a mug,

3.      Filtration

Make a filter paper and than pour the water. [refer book ]

JOURNEY OF WATER TO OUR HOME

The clean water we get in our taps is first treated before being supplied.

Water is treated by

1.      sedimentation,

2.      filtration, chlorination and

3.      storage {refer book page 107}