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question_answer1) Why do we tend to fall outwards when a car takes a steep turn?
question_answer2) An athlete always runs some distance before taking a jump. Why?
question_answer3) Two similar vehicles are moving with the same velocity on the roads such that one of them is loaded and the other is empty. Which of the vehicles will require larger force to stop it? Give reasons.
question_answer4) Is it possible that the train in which you are sitting appears to move while it is at rest?
question_answer5) Which has more inertia, a table tennis ball or a rubber ball of the same size?
question_answer6) Apart from changing the magnitude of velocity of an object (or) changing the direction of motion of an object, what other changes can force bring on an object?
question_answer7) You are applying force on the pan of single pan weighing balance and the pointer points to 100 g. What is the force in Newton's applied by you?
question_answer8) While riding on the bicycle, if we stop peddling, why does the bicycle begin to slow down?
question_answer9) Velocity-time graph of a moving particle of mass 1 kg is shown in figure. Is any force acting on the body? Justify your answer. Hence, no unbalanced force acts on the body.
question_answer10) How is force related to acceleration produced in a body by its application?
question_answer11) Athletes in pole jump events fall on cushioned surface and not on floor. Why?
question_answer12) A balloon is inflated and released. Why does it fly forward as air escapes out of it?
question_answer13) If action and reaction are equal and opposite forces, then why do not they cancel each other?
question_answer14) An automobile vehicle has a mass of 1500 kg. What must be the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of
question_answer15) Using a horizontal force of 200 N, we intend to move a wooden cabinet across a floor at a constant velocity. What is the frictional force that will be exerted on the cabinet?
question_answer16) If action is always equal to the reaction, explain how a horse can pull a cart?
question_answer17) Place a water filled tumbler on a tray. Hold the tray and turn around as fast as you can.
question_answer18) Why does water not pull?
question_answer19) Does Newton's third law apply to a system where bodies do not actually touch each other?
question_answer20) What did Galileo conclude on the basis of his experiments on the motion of objects?
question_answer21) Why mass is sometimes called coefficient of linear inertia?
question_answer22) What is the net momentum of gun and bullet system before firing?
question_answer23) What is the net momentum of gun and bullet system after firing?
question_answer24) Why should we wear safety seat belts in a car?
question_answer25) Dry leaves fallen on ground from trees blow off with wind, while fruits do not. Why?
question_answer26) If F and F' are balanced forces, what will be the magnitude of ?
question_answer27) A body accelerates when balanced force acts on it. Is it true or false? Why?
question_answer28) How is force related to momentum of a body?
question_answer29) If is force exerted on a body and is the reaction force exerted by the body, relate and ?
question_answer30) Relate SI unit of momentum with its CGS unit.
question_answer31) Why is a person hurt less when he falls on a spongy surface?
question_answer32) State a relation for velocity of rocket at any instant of time.
question_answer33) Which law can explain the process of recoil of gun?
question_answer34) According to the third law of motion, action and reaction force act on same body or different bodies.
question_answer35) A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. Explain.
question_answer36) A passenger in a moving train tosses a coin which falls behind him. From this incident, what you can predict about the motion of train.
question_answer37) A water tanker filled up to of its height is moving with a uniform speed. On sudden application of the brake, in which direction the water in the tank would flow?
question_answer38) What do you mean by a resultant force?
question_answer39) Give two examples of effects of force.
question_answer40) Name the agency which when applied to a body is directly proportional to the rate of change of momentum which it produces in the body.
question_answer41) Define inertia and list its types. Give two examples to discribe each type.
question_answer42) Derive the mathematical relation of Newton's second law of motion.
question_answer43) Using second law of motion derive the relation between force and acceleration. A bullet of 10 g strikes a sand-bag at a speed of 103 m/s and gets embedded after travelling 5 cm. Calculate (i) the resistive force exerted by sand on the bullet (ii) the time taken by bullet to come to rest.
question_answer44) A bullet of mass 20 g is horizontally fired with a horizontal velocity 150 from a pistol of mass 2 kg. What is the recoil velocity of the pistol?
question_answer45) A boy of mass 40kg jumps with a horizontal velocity of 5 ms~1 onto a stationary cart with frictionless wheels. The mass of the cart is 3 kg. What is his velocity as the cart starts moving? Assume that there is no external unbalanced force working in horizontal direction.
question_answer46) Derive the unit of force using the second law of motion. A force of 5 N produces an acceleration of on a mass and an acceleration of on a mass . What acceleration would the same provide if both the masses are tied together?
question_answer47) What is momentum? Write its SI unit. Interpret force in terms of momentum. Represent the following graphically momentum versus velocity when mass is fixed. (ii) momentum versus mass when velocity is constant.
question_answer48) (i) Name the property of bodies to resist a change in their velocity. (ii) What is the relationship between force and acceleration ? (iii) What name is given to the product of mass and velocity of a body? (iv) Which physical quantity corresponds to the rate of change of momentum? (v) Name the principle on which a rocket works.
question_answer49) Give reasons (i) It is difficult to balance our body, when we accidentally step on a peel of a banana. (ii) Pieces of bursting cracker fall in all possible directions. (iii) A glass pane of a window is shattered, when a flying pebble hits it. (iv) It is easier to stop a tennis ball than a cricket ball moving at the same speed. (v) A javelin thrower is marked foul, if an athlete crosses over the line marked for the throw. Athletes often fail to stop themselves before the line. (i) The reason is that one cannot exert action force effectively on the slippery peel of banana in the backward direction. Hence, in response the ground does not exert sufficient reaction the force in forward direction and hence we lose our balance. (ii) This can be explained on the law of conservation of momentum. When due to explosion some pieces move in the same particular direction, then in order to conserve momentum the remaining pieces move in the opposite direction. (iii) The reason is that, the glass pane of the window is a hard solid. The flying pebble suffers change in momentum in a very short time, so the force exerted by the glass window on the pebble will be large. Consequently the glass pane of the window will shatter. (iv) The reason is that mass of the cricket ball is more than that of a tennis ball. Thus, momentum is more in case of the cricket ball due to larger mass as compared to the tennis ball. So, less force has to be applied in the case of the tennis ball to stop. (v) The reason is that when athletes are running for the throw then due to inertia of motion they often fail to stop themselves before the line. (1x5)
question_answer50) (i) Explain why is it difficult to walk on sand? (ii) Why is the recoil of a heavy gun, on firing, not so strong as that of a light gun using the same cartridge? (iii) A constant force acts on an object of 5 kg for a period of 2 s. It increases the velocity of an object from 3 m/s to 7 m/s. Find the magnitude of the applied force. Now if the force was applied for a period of 5 s, what would be the final velocity of the object?
question_answer51) The speed-time graph of a car of 1000 kg mass is given. On the basis of this, answer the following questions (i) When is the maximum force acting on car? (ii) What is the retarding force acting on the car? (iii) For how long is no force is acting on the car? (iv) What is the velocity of the car after 4 seconds? (v) Find the acceleration of the car during each of the first two intervals of four second each.
question_answer52) Name the scientist who proved for the first time that objects move with constant speed when no force acts on them.
question_answer53) Why do bicycles begin to slow down when we stop pedalling?
question_answer54) Which law of motion gives the measure of force?
question_answer55) Write the C.G.S unit of force.
question_answer56) Can every force produce motion in every object?
question_answer57) When a force is applied to a body, what are the two essential effects it can produce?
question_answer58) Define 1 newton force.
question_answer59) What do you mean by an impact force?
question_answer60) Define force of friction.
question_answer61) Define electrostatic force.
question_answer62) If the body is found to be accelerated, is the force acting on it balanced or unbalanced?
question_answer63) What do balanced forces usually do to a body?
question_answer64) When a body moves on flat surface, will its speed change?
question_answer65) What did Galileo conclude on the basis of his experiments on the motion of objects?
question_answer66) What do you mean by a resultant force?
question_answer67) Do action and reaction act on the same body?
question_answer68) Plot a graph between forces applied on a body and the acceleration produced in the given mass, assuming that the magnitude of force is constantly changing.
question_answer69) Write the SI unit of impulse.
question_answer70) What is the total momentum of a bullet and a gun before firing?
question_answer71) Name the principle on which a rocket works.
question_answer72) Body A is heavier than body Q. Which has more inertia?
question_answer73) A body is moving with uniform acceleration. Is its momentum constant?
question_answer74) Name the physical quantity that corresponds to the rate of change of momentum.
question_answer75) Which principle is involved in the working of a jet plane?
question_answer76) Why mass is sometimes called coefficient of linear inertia?
question_answer77) When a force acting on a body has equal and opposite reaction, then why should the body move at all?
question_answer78) Does Newton's third law apply to a system where bodies do not actually touch each other?
question_answer79) Suppose a ball of mass m is thrown vertically upwards with an initial speed v, its speed decreases continuously till it becomes zero. Therefore, the ball begins to fall downward and attains the speed v again before striking the ground. It implies that the magnitude of initial and final momenta of the ball are same. Yet, it is not an example of conservation of momentum. Explain why.
question_answer80) Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (b) a five-rupee coin and a one-rupee coin?
question_answer81) Deduce Newton's first law from the second law.
question_answer82) In the following example, try to identify the number of times the velocity of ball changes: "A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team". Also identify the agent supplying the force in each case. [NCERT]
question_answer83) What is the ratio of SI units to CGS units of momentum? How do you measure the effect of an impulsive force on the body?
question_answer84) Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?
question_answer85) Explain why some of the leaves may get detached from a tree if we vigorously shake its branch. [NCERT]
question_answer86) When small boy is trying to push a heavy stone, mention various forces acting on the stone.
question_answer87) On which factors does friction depend?
question_answer88) A bullet fired against a glass window pane makes a hole in it, and the glass pane is not cracked. But on the other hand, when a stone strikes the same glass pane, it gets smashed. Why is it so?
question_answer89) Describe in brief an activity to illustrate the property of inertia of rest.
question_answer90) Why can a small mass such as a bullet kill a person when fired from a gun?
question_answer91) Why does a boat tend to leave the shore, when passengers are alighting from it?
question_answer92) Give few examples of Newton's third law of motion.
question_answer93) Describe our walking in terms of Newton's third law of motion.
question_answer94) There are three solids made up of aluminium, steel and wood, of the same shape and same volume. Which of them would have highest inertia? [NCERT Exemplar]
question_answer95) Two friends on roller-skates are standing 5 m apart facing each other. One of them throws a ball of 2 kg towards the other, who catches it. How will this activity affect the position of the two? Explain your answer.
question_answer96) A batsman hits a cricket ball which then rolls on a level ground. After covering a short distance, why does the ball come to rest?
question_answer97) Why does a cricket player moves his hand backward while catching the ball?
question_answer98) Why does an athlete puts some sands or cushion on the ground while high jumping?
question_answer99) Describe balanced forces with the help of two examples.
question_answer100) When a carpet is beaten with a stick, dust comes out of it. Explain. [NCERT]
question_answer101) Why is it advised to tie any luggage kept on the roof of a bus with a rope? [NCERT]
question_answer102) Why do the driver and the person seated in front seat need a seat belt?
question_answer103) Akhtar, Kiran and Rahul were riding in a motor car that was moving with a high velocity on an expressway when an insect hit the windshield and got struck on the windscreen. Akhtar and Kiran started pondering over the situation. Kiran suggested that the insect suffered a greater change in momentum as compared to the change in momentum of the motor car (because the change in velocity of the insect was much more than that of motor car). Akhtar said that since the motor car was moving with a larger velocity, it exerted a larger force on the insect; and as a result the insect died. Rahul while pulling on a new explanation that the both the motor car and the insect experienced the same force and a change in their momentum. Comment on these suggestions. [NCERT]
question_answer104) Water sprinkler used for grass lawns begins to rotate as soon as as the water is supplied. Explain the principle on which it works.
question_answer105) According to third law of motion when we push on an object, the object pushes back on us with 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 equal and opposite forces cancel each other. Comment on this logic and explain why the truck does not move. [NCERT]
question_answer106) Describe Newton's first law of motion in detail, giving examples.
question_answer107) Derive the mathematical relation of Newton's second law of motion.
question_answer108) Derive the mathematical formula of conservation of momentum.
question_answer109) If action is always equal to the reaction, explain how a horse can pull a cart. [NCERT]
question_answer110) An object experiences a net zero external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity? If yes, state the conditions that must be placed on the magnitude and direction of the velocity. If no, provide a reason. [NCERT]
question_answer111) What is the relationship between mass and inertia? Explain with the help of examples.
question_answer112) Describe Newton's third law of motion.
question_answer113) Why does an athlete run a certain distance before taking a leap?
question_answer114) Two balls of the same size of different materials, rubber and iron are kept on the smooth floor of a moving train. The brakes are applied suddenly to stop the train. Will the balls start rolling? If so, in which direction? Will they move with the same speed? Give reasons for your answer.
question_answer115) The velocity-time graph of an object of mass m = 50 g is shown in figure. Observe the graph carefully and answer the following questions. (a) Calculate the force on the object in time interval 0 to 3 s. (b) Calculate the force on the object in the time interval 6 to 10 s. (c) Is there any time interval in which no force acts on the object? Justify your answer.
question_answer116) If an object is not moving, does it mean that no force is acting on it?
question_answer117) Take a test tube and pour a small amount of water in it. Seal its mouth with the help of a cork. Heat the test tube on a burner flame till all water turns into steam. (i) What happens to the cork? (ii) Why does it happen? (iii) What might happen in case, cork was too tightly closed?
question_answer118) Two hockey players of opposite teams, while trying to hit a hockey ball on the ground, collide and immediately get entangled. One has a mass of 60 kg and was moving with a velocity of 5 m/s. The other has a mass of 55 kg and was moving with a velocity of 6 m/s, towards the first player. In which direction and with what velocity will they move after they become entangled? Assume that the frictional force acting between the feet of two players and ground is negligible.
question_answer119) Describe an activity to demonstrate Newton's third law of motion.
question_answer120) Give reasons for the following. (i) Horse continues to apply force in order to move a cart with constant speed. (ii) Water sprinkler used for grass lawns begins to rotate as soon as water is supplied. (iii) Water drops are removed from wet clothes by giving tight jerk to the cloth.
question_answer121) Force of 10 N applied to a mass \[{{m}_{1}}\] produces an acceleration of 5 \[\text{m}{{\text{s}}^{\text{-2}}}\] and when applied to mass \[{{m}_{2}}\], produces an acceleration of 15 \[\text{m}{{\text{s}}^{\text{-2}}}\]in the mass. How much acceleration will the same force produce if the two masses are tied together?
question_answer122) An iron sphere of mass 1 kg is dropped from a height of 10 m. If the acceleration of sphere is 9.8 \[\text{m}{{\text{s}}^{-2}}\], calculate the momentum transferred to the ground by the ball.
question_answer123) A bullet of mass 4 g when fired with a velocity of 50 ms -1, can enter a wall up to a depth of 10 cm. How much will be the average resistances offered by the wall?
question_answer124) A cracker of mass 100 g explodes into two pieces of equal mass. Show that these two pieces of the cracker fly in opposite direction.
question_answer125) The velocity-time graph of a ball moving on the surface of floor is shown in figure. Calculate the force acting on the ball if mass of the ball is 100 g.
question_answer126) A body of mass 300 g kept at rest breaks into two parts due to internal forces. One part of mass 200 g is found to move at a speed of 12 m/s towards the east. What will be the velocity of the other part?
question_answer127) A bullet of mass 0.02 kg is fired from a gun weighing 7.5 kg. If the initial velocity of the bullet is 200 m/s, calculate the speed with which the gun recoils.
question_answer128) A rifle of mass 3 kg fires a bullet of mass 0.03 kg. The bullet leaves the barrel of the rifle at a velocity of 100 m/s. If the bullet takes 0.003 s to move through its barrel, calculate the force experienced by the rifle due to its recoil.
question_answer129) Look at the diagram below and answer the following questions. (i) When a force is applied through the free end of the spring balance A, the reading on the spring balance A is 15 g wt. What will be the measure of the reading shown by spring balance B? (ii) Write reasons for your answer. (iii) Name the force which balance A exerts on balance B and the force of balance B on balance A.
question_answer130) The motion of a body of mass 5 kg is shown in the v-t graph. Find from graph. (i) it acceleration. (ii) the force acting on the body (iii) the change in momentum of body in 2 seconds after start.
question_answer131) Glass wares are wrapped in straw during their transportation. Justify giving reason.
question_answer132) The force of friction between the surface of a floor and the surface of a box in contact with the floor in 200 N. We wish to move the box on the floor with constant velocity. How much force has to be applied on the box?
question_answer133) A boy pulls a table along the floor of a room. (i) Name the forces acting on the table. (ii) Which of these forces perform positive work? (iii) Which of these forces perform negative work?
question_answer134) Give reasons and mention the law related to these statements. (i) It is easier to push an empty box than to push the box full of books. (ii) It is difficult for a fireman to hold a hose which ejects large amount of water with high velocity.
question_answer135) A cracker of mass 100 g explodes into two pieces of equal mass. Show that these two pieces of the cracker fly in opposite direction.
question_answer136) Two friends were playing 'catch the ball' in a park. A was able to catch the ball comfortably without hurting himself, while 'B' was hurt every time he caught a ball. Finally B asked A how he could catch the ball with ease. A explained the phenomena to B. B thanked him. (i) Why was A not hurt while catching the ball? (ii) Compare and contrast the values of A and B.
question_answer137) In order to find out force exerted by his car, Manoj plotted a velocity-time graph for his journey along a straight highway. He wondered if he did not accelerate after 1 min, where was the fuel spent by engine going. His wife then told him how his car was overcoming friction due to road. (i) What are the values of Manoj? (ii) With what values is his wife equipped with? (iii) How will they find their total displacement?
question_answer138) William was having a gun-shoot session in a training camp. As soon as he shot a bullet, he fell backwards. Sanat started making fun of him. William stood up and explained the cause of this effect and told him not to laugh without understanding the scientific cause behind it. (i) What explanation did William give to Sanat? (ii) Compare and contrast the values of William and Sanat. (iii) If you were in place of Sanat, how would you react to such a situation?
question_answer139) Two friends of class IX were sitting in a restaurant and try to push a pillar with all their might. The first one explains the situation that the pillar did not move because of its inertia while the second one says that it is because action and reaction forces cancel each other's effect. (i) Which of the two friends give correct justification? (ii) Compare the values of both the boys. (iii) If Newton's third law holds good, why don't action and reaction forces cancel each other when we walk?
question_answer140) Mahi is fond of trying stunts. She jumps on a stationary cart while playing. Since cart wheels are frictionless, the cart begins to move forward and stops after covering some distance. Mahi probes to find out reasons for such observation and gives a correct interpretation too. (i) What values of Mahi will you appreciate? (ii) What qualities of Mahi according to you, need to be modified? (iii) What were Mahi's interpretations?
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