1. An object of mass 2 kg is sliding with a constant velocity of 4 m/ s on a frictionless horizontal table. The force required to keep the object moving with the same velocity is
(a) 32 N (b) 0 N (c) 2 N (d) 8 N (b]
2. Rocket works on the principle of conservation of
(a) mass (b) energy (c) momentum (d) velocity [c]
3. A car is moving at 45 km/hr.A constant force acts on the car for 10 sc .So that it's velocity becomes 63 km/hr .The distance travelled by car during this interval of 10 sec is :
a) 100 m b) 150 m c) 200 m d) 50 m [b]
What is the definition of balanced and unbalanced force?
When two equal forces acting on an object in opposite directions called balanced force. When something does not move the forces are balanced, e.g. Gravity pulls a table down but that table is pushed up by the floor or the ground it stands on so doesn’t’ move.
An Unbalanced force is needed for something to change movement or change direction, e.g. aseesaw moving up and down because the forces are not equal.
Net force: - The sum of all the forces acting on a body is known as net force.
Difference between Balanced force and unbalanced force.
Balanced force:- If net force on a body is zero it is called balanced force. Balanced forces do not cause a change in motion. They are equal in magnitude and opposite in direction. Therefore, the resultant of these forces will be zero.
Example: Two persons pushing a box with the same force in opposite directions.
Unbalanced forces:- If net force on a body is non-zero it is called unbalanced force.
Forces whose resultant is not equal to zero are called unbalanced forces. For example: An arm wrestling competition among a strong person and a weak one. The resultant force will be in the direction of the force applied by the strong person.
What Is Inertia
By Newton's law we know that ,a body at rest will remain at rest and a body in motion will continue in a straight line unless it is compelled by an external force.This tendency of a body is called inertia.So we can say that 'Inertia is that property of a body due to which it resists a change in its state of rest or of uniform motion.'
When the brakes are applied to the bike the back seater moves forward why?
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IX Force and laws of motion solved questions: NCERT / CBSE Textbook Exercise Questions Solved
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Question 1: What is a good source of energy?
Answer: A good source of energy fulfils the following criteria:
(I)It produces a lot of heat per unit mass.
(II) It does a huge amount of work per unit mass.
(III) It is easily accessible.
(IV) It is easy to store and transport.
(V)It is economical.
(VI)It produces less amount of smoke.
Question 2: What is a good fuel?
Answer: A good fuel produces a huge amount of heat on burning, does not produce a lot of smoke, and is easily available.
Question 3: If you could use any source of energy for heating your food, which one would you use and why?
Answer: Natural gas can be used for heating and cooking food because it is a clean source of energy. It does not produce huge amount of smoke on burning. Although it is highly inflammable, it is easy to use, transport, and it produces a huge amount of heat on burning.
Question 4: What are the disadvantages of fossil fuels?
Answer: The disadvantages of fossil fuels are as follows:
(a) Burning of coal and petroleum produces a lot of pollutants causing air pollution.
(b) Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause acid rain,which affects the soil fertility and potable water.
(c) Burning of fossil fuels produce gases such as carbon dioxide that causes global warming.
Question 5: Why are we looking at alternate sources of energy?
Answer: Fossil fuels, which have been traditionally used by human beings as an energy sources, are non-renewable sources of energy. These sources of energy are limited and cannot replenish on their own. They are being consumed at a large rate. If this rate of consumption continues, then the fossil fuels would be exhausted from the Earth.
Therefore, we have to conserve the energy sources. Hence, we should look for alternate sources of energy. Download full File
10th Chapter : Source of Energy Notes and MCQ's
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10th Chapter : Source of Energy Notes and MCQ's
1. Fill in the blanks:-
(a) New cells are formed from pre-existing cells.
(b) Movement of water molecules from their higher concentration to their lower concentration through a semi- permeable membrane is called Osmosis.
(c) The functional components of cell are plasma membrane, cytoplasm & nucleus.
(d) Protoplasm has two parts- cytoplasm & nucleoplasm.
(e) Nucleus, mitochondria & plastids have their own DNA & ribosomes.
(f) The shrinkage or contraction of the contents of the cell away from the cell wall is known as plasmolysis.
(g) The process by which Amoeba can engulf a food particle is endocytosis.
(h) Biogenesis is the manufacture of lipids required for making cell membrane.
(i) A cell that lacks nuclear membrane is called a prokaryotic cell & the nuclear region is called nucleoid.
(j) Movement of materials in & out of the cell takes place by diffusion & osmosis.
2. What is the advantage of multicellularity over unicellularity?
Ans- Division of labour.
3. What are the chromosomes made up of?
Ans- DNA & proteins
4. A cell placed in a solution swells up. What kind of solution is it? Why does it happen?
Ans- It is a hypotonic sol ution & water enters the cell by endosmosis causing the cell to swell up.
5. Why are lysosomes known as “suicidal bags”?
Ans- They secrete powerful digestive enzymes to digest the worn out and damaged cell
organelles as well as the cell itself when it loses its functional ability.
6.Why is the nucleus so significant in a cell?
Ans- Nucleus has the following important functions-
(i) It controls all cell activities
(ii) It contains hereditary material that transmits hereditary information from one
generation to the next
(iii) It helps in cell division
7. Differentiate between plant and animal cells.
1. PLANT CELL
1- Surrounded by two membranes- cell wall & cell membrane.
2- Possess three types of plastids chloroplasts, chromoplasts, leucoplasts.
3- Do not possess lysosomes.
4- Nucleus is towards the periphery.
5- Centrioles are absent
1- Surrounded only by cell / plasma membrane.
2-Do not possess plastids.
3-Possess lysosomes4-Nucleus is in the center ..
5-Centrioles present & help in cell division.
8. Give the major functions of the following cell organelles-
(a) Endoplasmic reticulum
RER-- Synthesis of proteins as it has ribosomes attached to it
SER- Synthesis of lipids required for making cell membrane
(b) Golgi apparatus-----------Storage & packaging of various products.
(c) Mitochondria------Production of ATP(Adenosine Triphosphate) which is a source of energy.
(d) Ribosomes ---Protein synthesis
(e) Golgi ApparatusStorage & packaging of various products.
f) LysosomesDigestion of worn out & damaged organelles
CBSE SOLVED TEST PAPERS CLASS - IX Science (Is matter around us pure)
Q. What is distillation?
Ans: Distillation is a method of separating mixtures based on differences in their boiling points. The compound which have higher boiling point will distillate later while the compound which have lowest boiling point will distillate out first.
Q. How is blood a heterogeneous substance?
Ans: Blood is a heterogeneous mixture because it a mixture of plasma, blood cells, glucose, proteins, mineral ions, hormones and many different salts dissolved in it. Thus the dispersed phase and dispersed medium are in different physical state and hence a heterogeneous mixture
Q. Calculate the mass of sodium sulphate required to prepare its 20% ( mass percent ) solution in 100g of water?
Ans: Mass % of Sodium sulphate in the solution = 20%
If the total mass of the solution = 100g Then mass of sodium sulphate = (20/100)x100 = 20 g
Mass of water = 100-20 = 80 g.
Q. Arun has prepared 0.01% ( by mass ) solution of sodium chloride in water, calculate the composition of soltution. How do you do it ?
Ans: Mass % of solute = 0.01 % of NaCl in water
Mass % of solute = [Mass of solute in grams / Mass of solution in grams] x 100.
Let us suppose that mass of the solution is 100 g.
Therefore mass of NaCl = 0.01 g
Mass of water = 100-0.01 = 99.99 g.
Q. How to separate components from mixture containing sulphur, charcol , pottasium nitrate?
Ans: The mixture containing sulphur, charcoal and potassium nitrate can be separated by following technique:
A. Add water to the mixture. Potassium nitrate will dissolve in water. Filter the solution.
B. Filterate is solution of potassium nitrate and residue contains sulphur and charcoal.
C. Evaporate the filterate, water will vapourize leaving behind potassium nitrate.
D. To the residue containing sulphur and charcoal add carbon disulphide, this will dissolve sulphur.
E. Filter this solution.
F. The filtrate will contain sulphur dissolved in carbon disulphide and residue will be charcoal.
G. Evaporate the filtrate, to obtain crystals of Sulphur.
Q. Acetone evaporates in normal room temp. Why do we have to heat it to its boiling point?
Ans: At room temperature the rate of evaporation of acetone is slow, to speed up the process to evaporate all the acetone in the mixture, we supply heat.
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X Triangles :Criteria for Similarity of Triangles Solved:
The surroundings where organisms live naturally are called its habitat.
Plants and animals have special features that help them to survive in their own habitat
Habitat can be terrestrial or aquatic.
Terrestrial habitat: the land where all plants and animals survive is called territorial habitat .For example: deserts, forests and grasslands, as well as coastal and mountain regions. Camels and cactus plants live in deserts only.
Aquatic habitat: The water where plants and animals survive is known as aquatic habitat like rivers, ponds, lakes, ocean and swamps. For example, fish live in water.
Adaptation: Plants and animals develop certain habits that help them survive in their surroundings, and this is known as adaption.
Acclimatization: The small adjustments by the body to overcome small changes in the surrounding atmosphere for a short period of time are called acclimatization.
Biotic and Abiotic components: These are living and non living components of a habitat .
Biotic components include all the livings organisms in a habitat like plants and animals .it is further classified into producers ,consumers , scavengers’ and decompose
Abiotic components include all the non-living things in a habitat like air, water, soil, sunlight and heat.
Q. What is the name for food producer? Ans: Autotrophs.
Q. Is desert habitat terrestrial or aquatic? Ans: terrestrial
Q. What is the term used to describe the response of plant and animals to light?
Ans: Photo tropism
Q. What we name the Plants growing in dry desert area ?
Q. What is decomposer?
Ans: Organism that feed on the dead and decay remains of plants and animal is called decomposer. Eg. Microorganism like bacteria and fungi.
Q. How are decomposers helpful to us?
Ans: Decomposer help to break down dead plants and animal into organic matter that increase fertility of soil .
Q. What are scavengers?
Ans: Living organism feed on dead animals helps to clean environment are called scavengers like vulture, crow , jackal etc.
Q. What type of consumer are carnivores?
Ans: Secondary consumer as the feed indirectly on plants for example tiger , lions, wolves etc
Q. State any two flight adaptation seen in areal animals?
Ans: Two flight adaptations seen in areal animals are: (a) Body modified like boat to minimize air resistance
(b) The limbs are modified into wings
Q. Define: (a) Epiphytes (b) Pneumatic bones (c) Nictitating membrane
Ans: (a) Roots of some plants like Spanish moss and some fern grow on other plants or tree to get sunlight is known as Epiphytes.
(b)The animals that can fly have hollow bones that are called Pneumatic bones. Like bones of birds
(c) The membrane that protect eyes of fish under water is called Pneumatic bones
Q. Discuss the adaptation seen in desert animals?
Ans: The adaptations seen in desert animals are:
(a) Store extra water in their body (b) Lives in deep borrow
(c) Try to avoid body contact with hot ground (d) Having long eye lash to protect eyes from sand
Q. How does temperature affect plants and animals?
Ans: Temperature affects the structure of leaves and stem of plants. Temperature affects the colouration of some birds and animals. Temperature also affects the size and body parts of animals.
Q. Biotic and abiotic component are dependants on each other Explain?
Ans: Animals depends on plants for food. Plants depend on light, air, soil and water for preparation of food. Therefore, biotic components directly or indirectly depend on abiotic components. Decomposers break down dead biotic components into organic matter that enrich soil. Photosynthesis help to maintain balance of gases in air and water in nature.
Q.What we call the plants that grow in moist habitat? Ans: Mesophytes
Q. what is the meaning of oviparous and viviparous
Ans: Oviparous are those animals which lay eggs example- crow, lizard where as viviparous are those animals which do not lay eggs and give birth to young ones for example- lion, dog.
Q. How is a cactus adapted to survive in a desert?
Ans: Cactus has a waxy surface with lots of water in it. it also has thorns to prevent loss of water. This is how it lives in the desert. it also lives just because of its thick fleshy stem.
Q. What is acclimisation?
Ans: The small problems some time occur in the body of organism over short period , The process of overcoming small changes in the surroundings is called acclimisation.
Q. How do plants and animals adapt themselves?
Ans: Plants and animals adapt themselves to different surroundings with the help of adaptive features they have. For Example: Presence of wings, flight muscles and a stream-lined body helps birds in flight. Birds also have hallow bones that make their body light. Presence of fur on the body of the polar bear which protects it from the cold temperature.
Q. Write two adaptive features in frog which help them to stay both of them water and land.
Ans: Frogs have moist skin for exchange of gases in water and they have lungs to breath in air
Q. Give reasons: a) Why are deep sea worms blind? b) Why are some marine creatures living in the deep sea give out light of there of own? c) Why the upper surface of the leaves of lotus have a thick cuticle ?
Ans: a. As we move deep into seas and oceans the amount of light or the visibility decreases. Deep sea worms are blind because of the lack of requirement. Some worms have large eyes but those are not for the purpose of seeing. These worms have developed strong sense of smell to encounter these problems.
b. Since there is lack of light in deep seas, some organisms can give out light to assist them in finding their way in the dark. This also helps them in finding prey to feed on and can also be used to find a mating partner.
C. Lotus is an aquatic plant. The leaves of the lotus plant have a thick waxy cuticle that helps in repelling water and keeps the stomata open so that water transport occurs effectively in plant
Q. why do cockroaches hide their face when sunlight falls on them?
Ans: Cockroaches have some light receptors cells in their eyes which cannot tolerate the high intensity light. This is the reason why they run toward darker areas during sunlight.
Things, which do not grow, move, or respond are called non-living things.
Things that grow, breathe, and respond are called living things.
PROPERTIES OF LIVING THINGS
(a) All living things grow: Infant grows into a child, Plants grow from seeds, Puppies grow into dogs, and kittens grow into cats.
(b) All living things can move: Living things move from place to place in search of food iscalled Locomotion
(c) All living things need food to live: Living things eat food to get energy to live.
(d) All living things Respire: Living things eat and digest foods that get oxidized in body to release energy. This process is called Respiration. Respiration occurs inside body. Exchange of carbon dioxide and oxygen in living body is called breathing. Breathing occur outside the body. Plant breath through stomata and animal through nose. Small animal and microbes exchange gases by diffusion.
(e) All living things reproduce: Living things can produce young one of similar kinds. This process is called reproduction. Some animal give birth to young ones like dog, cow; Some animal lay eggs like bird, hen ; Plant grow from seeds ,stem and root etc.
(f) All living things respond: Living things can respond against touch, heat, light and gravity called stimulus. Change in our surrounding that make living things respond to them, are called stimuli. Touch me not plant show response to touch and its leaves hang down.
(g) All living things are made up of different kinds of cells. Group of cell is called tissue. Group of tissue is called organ. A group of organs is called organ system that work together to keep our body live.
(h) Living things excrete: Living Things throw waste outside body like sweat, urine, faeces. This process is called excretion. Plants excrete gum, leaves, latex etc
Q. What is habitat?
Answer: The surroundings where plants and animals live, is called their habitat. The presence of specific features, which enable a plant or an animal to live in particular habitat, is called adaptation.
Q. Which organism grow throw their lives
Q1. Define force and its SI unit?
Q 2. Distinguish between balanced and unbalanced force?
Q3. State three laws of motion?
Q 4. What is inertia? Is inertia vector quantity. Justify?
Q5. What is impulse? Prove that Impulse is equal to change in momentum?
Q. 6. Define momentum and Prove that F = ma
Q 7. Is it possible that a body keeps on moving with uniform velocity with? If yes give reason also name scientist who explained this statement?
Q 8. Why a person sitting in bus fall forward when moving bus suddenly stops?
Q9. Why people sitting in bus fall backward when bus suddenly starts?
Q10. Why dust fall on beating carpet with stick?
Q11. Why leaves fall when we are shacking branch of tree?
Q12. Why an athlete runs certain distance before taking long jump?
Q13. When bus takes u turn, passengers sitting inside thrown a side. Why?
Q14. Explain why it is difficult for a fireman to hold a hose, which ejects large amount of water at a high velocity.
Q15. How a karate player can break a pile of tiles with a single blow of his hand?
Q.16. Why does a bullet when fired against a glass window pane make a hole in it, and the glass pane will smash it?
Q.17. Why is it advised to tie a rope on the luggage while you travel by the bus?
Q18.Why vehicles are provided with shocker?
Q19. Why does a bicycle begin to slow down when we stop pedaling?
Q20. State and verify the law of conservation of momentum?
Q21. When we hit at the bottom of the pile of carom coins, other coins fall vertically on the carom board why?
Q22. Two balls A and B of masses 'm' and '2 m' are in motion with velocities '2 v' and 'v' respectively. Compare
(i) their inertia (ii) their momentum and (iii) the force needed to stop them in the same time
Q 23. A 8000 kg engine pulls a train of 5 wagons, each of 2000 kg, along a horizontal track. If the engine exerts a force of 40,000 N and the track offers a friction force of 5,000 N then calculate:
(a) the net accelerating force (b) the acceleration of the train (c)the force of the wagon 1 on rest of the wagons.
Q 24.According to the third law of motion when we push on an object, the object pushes back on us with an equal and opposite force. If the object is a massive truck parked along the road side, it will probably not move. A student justifies this by answering that the two opposite and equal forces cancel each other. Comment on this logic and explain why the truck does not move.
Q25.A machine gun can fire 50 g bullets with a velocity of 150 m/s. A 60 kg stone is moving towards the machine gun velocity of 10 m/s. How many bullets must be fired from the gun to just stop the stone in its tracks?
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